Ôn Tập Chương 3
Hướng dẫn giải Bài 56 (Trang 34 SGK Toán Đại số 8, Tập 2)
<p>Đề bài:</p>
<p>Để khuyến khích tiết kiệm điện, giá điện sinh hoạt được tính theo kiểu lũy tiến, nghĩa là nếu người sử dụng càng dùng nhiều điện thì giá mỗi số điện <span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">(</mo><mn>1</mn><mi>k</mi><mi>W</mi><mi>h</mi><mo stretchy="false">)</mo></math>"><span id="MJXc-Node-1" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-2" class="mjx-mrow"><span id="MJXc-Node-3" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-4" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">1</span></span><span id="MJXc-Node-5" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">k</span></span><span id="MJXc-Node-6" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">W</span></span><span id="MJXc-Node-7" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">h</span></span><span id="MJXc-Node-8" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span></span></span></span> càng tăng lên theo các mức như sau:</p>
<p>Mức thứ nhất: Tính cho 100 số điện đầu tiên;</p>
<p>Mức thứ hai: Tính cho số điện thứ <span id="MathJax-Element-3-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>101</mn></math>"><span id="MJXc-Node-12" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-13" class="mjx-mrow"><span id="MJXc-Node-14" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">101</span></span></span></span></span> đến <span id="MathJax-Element-4-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>150</mn></math>"><span id="MJXc-Node-15" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-16" class="mjx-mrow"><span id="MJXc-Node-17" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">150</span></span></span></span></span>, mỗi số đắt hơn <span id="MathJax-Element-5-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>150</mn></math>"><span id="MJXc-Node-18" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-19" class="mjx-mrow"><span id="MJXc-Node-20" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">150</span></span></span></span></span> đồng so với mức thứ nhất;</p>
<p>Mức thứ ba: Tính cho số điện thứ <span id="MathJax-Element-6-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>151</mn></math>"><span id="MJXc-Node-21" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-22" class="mjx-mrow"><span id="MJXc-Node-23" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">151</span></span></span></span></span> đến <span id="MathJax-Element-7-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>200</mn></math>"><span id="MJXc-Node-24" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-25" class="mjx-mrow"><span id="MJXc-Node-26" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">200</span></span></span></span></span>, mỗi số đắt hơn <span id="MathJax-Element-8-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>200</mn></math>"><span id="MJXc-Node-27" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-28" class="mjx-mrow"><span id="MJXc-Node-29" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">200</span></span></span></span></span> đồng so với mức thứ hai;</p>
<p>v.v…</p>
<p>Ngoài ra, người sử dụng còn phải trả thêm <span id="MathJax-Element-9-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>10</mn><mi mathvariant="normal">&#x0025;</mi></math>"><span id="MJXc-Node-30" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-31" class="mjx-mrow"><span id="MJXc-Node-32" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">10</span></span><span id="MJXc-Node-33" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">%</span></span></span></span></span> thuê giá trị gia tăng (thuế VAT).</p>
<p>Tháng vừa qua, nhà Cường dùng hết <span id="MathJax-Element-10-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>165</mn></math>"><span id="MJXc-Node-34" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-35" class="mjx-mrow"><span id="MJXc-Node-36" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span></span></span></span> số điện và phải trả <span id="MathJax-Element-11-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>95700</mn></math>"><span id="MJXc-Node-37" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-38" class="mjx-mrow"><span id="MJXc-Node-39" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">95700</span></span></span></span></span> đồng. Hỏi mỗi số điện ở mức thứ nhất giá là bao nhiêu?</p>
<p>Lời giải chi tiết:</p>
<p>Gọi <span id="MathJax-Element-19-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>x</mi></math>"><span id="MJXc-Node-113" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-114" class="mjx-mrow"><span id="MJXc-Node-115" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span></span></span></span> (đồng) là giá điện ở mức thứ nhất <span id="MathJax-Element-20-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>x</mi><mo>&gt;</mo><mn>0</mn></math>"><span id="MJXc-Node-116" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-117" class="mjx-mrow"><span id="MJXc-Node-118" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-119" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">></span></span><span id="MJXc-Node-120" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">0</span></span></span></span></span>.</p>
<p>Nhà Cường dùng hết 165 số điện mà <span id="MathJax-Element-21-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>165</mn><mo>=</mo><mn>100</mn><mo>+</mo><mn>50</mn><mo>+</mo><mn>15</mn></math>"><span id="MJXc-Node-121" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-122" class="mjx-mrow"><span id="MJXc-Node-123" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-124" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-125" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">100</span></span><span id="MJXc-Node-126" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-127" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">50</span></span><span id="MJXc-Node-128" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-129" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">15</span></span></span></span></span></p>
<p>Như vậy nhà Cường phải đóng cho 100 số điện ở mức 1, 50 số điện ở mức 2 và 15 số điện ở mức 3.</p>
<p>Số tiền phải trả ở mức 1 là: <span id="MathJax-Element-22-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>100</mn><mi>x</mi></math>"><span id="MJXc-Node-130" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-131" class="mjx-mrow"><span id="MJXc-Node-132" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">100</span></span><span id="MJXc-Node-133" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span></span></span></span> (đồng).</p>
<p>Số tiền phải trả ở mức 2 là: <span id="MathJax-Element-23-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>50</mn><mo stretchy="false">(</mo><mi>x</mi><mo>+</mo><mn>150</mn><mo stretchy="false">)</mo></math>"><span id="MJXc-Node-134" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-135" class="mjx-mrow"><span id="MJXc-Node-136" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">50</span></span><span id="MJXc-Node-137" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-138" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-139" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-140" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">150</span></span><span id="MJXc-Node-141" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span></span></span></span> (đồng).</p>
<p>Số tiền phải trả ở mức 3 là: <span id="MathJax-Element-24-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>15</mn><mo stretchy="false">(</mo><mi>x</mi><mo>+</mo><mn>150</mn><mo>+</mo><mn>200</mn><mo stretchy="false">)</mo><mo>=</mo><mn>15</mn><mo stretchy="false">(</mo><mi>x</mi><mo>+</mo><mn>350</mn><mo stretchy="false">)</mo></math>"><span id="MJXc-Node-142" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-143" class="mjx-mrow"><span id="MJXc-Node-144" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">15</span></span><span id="MJXc-Node-145" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-146" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-147" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-148" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">150</span></span><span id="MJXc-Node-149" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-150" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">200</span></span><span id="MJXc-Node-151" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-152" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-153" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">15</span></span><span id="MJXc-Node-154" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-155" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-156" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-157" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">350</span></span><span id="MJXc-Node-158" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span></span></span></span> (đồng).</p>
<p>Số tiền phải trả chưa tính thuế VAT là:</p>
<p><span id="MathJax-Element-25-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>100</mn><mi>x</mi><mo>+</mo><mn>50</mn><mo stretchy="false">(</mo><mi>x</mi><mo>+</mo><mn>150</mn><mo stretchy="false">)</mo><mo>+</mo><mn>15</mn><mo stretchy="false">(</mo><mi>x</mi><mo>+</mo><mn>350</mn><mo stretchy="false">)</mo></math>"><span id="MJXc-Node-159" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-160" class="mjx-mrow"><span id="MJXc-Node-161" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">100</span></span><span id="MJXc-Node-162" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-163" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-164" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">50</span></span><span id="MJXc-Node-165" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-166" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-167" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-168" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">150</span></span><span id="MJXc-Node-169" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-170" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-171" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">15</span></span><span id="MJXc-Node-172" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-173" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-174" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-175" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">350</span></span><span id="MJXc-Node-176" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span></span></span></span></p>
<p><span id="MathJax-Element-26-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mn>100</mn><mi>x</mi><mo>+</mo><mn>50</mn><mi>x</mi><mo>+</mo><mn>7500</mn><mo>+</mo><mn>15</mn><mi>x</mi><mo>+</mo><mn>5250</mn></math>"><span id="MJXc-Node-177" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-178" class="mjx-mrow"><span id="MJXc-Node-179" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-180" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">100</span></span><span id="MJXc-Node-181" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-182" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-183" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">50</span></span><span id="MJXc-Node-184" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-185" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-186" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">7500</span></span><span id="MJXc-Node-187" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-188" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">15</span></span><span id="MJXc-Node-189" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-190" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-191" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">5250</span></span></span></span></span></p>
<p><span id="MathJax-Element-27-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn></math>"><span id="MJXc-Node-192" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-193" class="mjx-mrow"><span id="MJXc-Node-194" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-195" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-196" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-197" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-198" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span></span></span></span></p>
<p>Số tiền thuế VAT là <span id="MathJax-Element-28-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mo>.</mo><mn>10</mn><mi mathvariant="normal">&#x0025;</mi></math>"><span id="MJXc-Node-199" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-200" class="mjx-mrow"><span id="MJXc-Node-201" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-202" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-203" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-204" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-205" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-206" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-207" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">.</span></span><span id="MJXc-Node-208" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">10</span></span><span id="MJXc-Node-209" class="mjx-mi"><span class="mjx-char MJXc-TeX-main-R">%</span></span></span></span></span><span id="MathJax-Element-29-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mn>.0</mn><mo>,</mo><mn>1</mn></math>"><span id="MJXc-Node-210" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-211" class="mjx-mrow"><span id="MJXc-Node-212" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-213" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-214" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-215" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-216" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-217" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-218" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-219" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">.0</span></span><span id="MJXc-Node-220" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">,</span></span><span id="MJXc-Node-221" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">1</span></span></span></span></span></p>
<p>Vì tổng số tiền phải trả là <span id="MathJax-Element-30-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>95700</mn></math>"><span id="MJXc-Node-222" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-223" class="mjx-mrow"><span id="MJXc-Node-224" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">95700</span></span></span></span></span> đồng nên ta có:</p>
<p><span id="MathJax-Element-31-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo>+</mo><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mn>.0</mn><mo>,</mo><mn>1</mn></math>"><span id="MJXc-Node-225" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-226" class="mjx-mrow"><span id="MJXc-Node-227" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-228" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-229" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-230" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-231" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-232" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-233" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-234" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-235" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-236" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-237" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-238" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">.0</span></span><span id="MJXc-Node-239" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">,</span></span><span id="MJXc-Node-240" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">1</span></span></span></span></span><span id="MathJax-Element-32-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mn>95700</mn></math>"><span id="MJXc-Node-241" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-242" class="mjx-mrow"><span id="MJXc-Node-243" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-244" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">95700</span></span></span></span></span></p>
<p><span id="MathJax-Element-33-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mn>1</mn><mo>+</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo stretchy="false">)</mo><mo>=</mo><mn>95700</mn></math>"><span id="MJXc-Node-245" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-246" class="mjx-mrow"><span id="MJXc-Node-247" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-248" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-249" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-250" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-251" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-252" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-253" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-254" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-255" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">1</span></span><span id="MJXc-Node-256" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-257" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">0</span></span><span id="MJXc-Node-258" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">,</span></span><span id="MJXc-Node-259" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">1</span></span><span id="MJXc-Node-260" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-261" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-262" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">95700</span></span></span></span></span></p>
<p><span id="MathJax-Element-34-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mn>.1</mn><mo>,</mo><mn>1</mn><mo>=</mo><mn>95700</mn></math>"><span id="MJXc-Node-263" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-264" class="mjx-mrow"><span id="MJXc-Node-265" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-266" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-267" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-268" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-269" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-270" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-271" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-272" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">.1</span></span><span id="MJXc-Node-273" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">,</span></span><span id="MJXc-Node-274" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">1</span></span><span id="MJXc-Node-275" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-276" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">95700</span></span></span></span></span></p>
<p><span id="MathJax-Element-35-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mo stretchy="false">(</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo stretchy="false">)</mo><mo>=</mo><mn>95700</mn><mo>:</mo><mn>1</mn><mo>,</mo><mn>1</mn></math>"><span id="MJXc-Node-277" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-278" class="mjx-mrow"><span id="MJXc-Node-279" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-280" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">(</span></span><span id="MJXc-Node-281" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-282" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-283" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-284" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-285" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">)</span></span><span id="MJXc-Node-286" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-287" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">95700</span></span><span id="MJXc-Node-288" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">:</span></span><span id="MJXc-Node-289" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">1</span></span><span id="MJXc-Node-290" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">,</span></span><span id="MJXc-Node-291" class="mjx-mn MJXc-space1"><span class="mjx-char MJXc-TeX-main-R">1</span></span></span></span></span></p>
<p><span id="MathJax-Element-36-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mn>165</mn><mi>x</mi><mo>+</mo><mn>12750</mn><mo>=</mo><mn>87000</mn></math>"><span id="MJXc-Node-292" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-293" class="mjx-mrow"><span id="MJXc-Node-294" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-295" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-296" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-297" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">+</span></span><span id="MJXc-Node-298" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span><span id="MJXc-Node-299" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-300" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">87000</span></span></span></span></span></p>
<p><span id="MathJax-Element-37-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mn>165</mn><mi>x</mi><mo>=</mo><mn>87000</mn><mo>&#x2212;</mo><mn>12750</mn></math>"><span id="MJXc-Node-301" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-302" class="mjx-mrow"><span id="MJXc-Node-303" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-304" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-305" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-306" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-307" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">87000</span></span><span id="MJXc-Node-308" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">−</span></span><span id="MJXc-Node-309" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R">12750</span></span></span></span></span></p>
<p><span id="MathJax-Element-38-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mn>165</mn><mi>x</mi><mo>=</mo><mn>74250</mn></math>"><span id="MJXc-Node-310" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-311" class="mjx-mrow"><span id="MJXc-Node-312" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-313" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">165</span></span><span id="MJXc-Node-314" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-315" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-316" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">74250</span></span></span></span></span></p>
<p><span id="MathJax-Element-39-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mi>x</mi><mo>=</mo><mn>74250</mn><mo>:</mo><mn>165</mn></math>"><span id="MJXc-Node-317" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-318" class="mjx-mrow"><span id="MJXc-Node-319" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-320" class="mjx-mi MJXc-space3"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-321" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-322" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">74250</span></span><span id="MJXc-Node-323" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">:</span></span><span id="MJXc-Node-324" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">165</span></span></span></span></span></p>
<p><span id="MathJax-Element-40-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false">&#x21D4;</mo><mi>x</mi><mo>=</mo><mn>450</mn></math>"><span id="MJXc-Node-325" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-326" class="mjx-mrow"><span id="MJXc-Node-327" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">⇔</span></span><span id="MJXc-Node-328" class="mjx-mi MJXc-space3"><span class="mjx-char MJXc-TeX-math-I">x</span></span><span id="MJXc-Node-329" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-330" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">450</span></span></span></span></span> (thỏa mãn điều kiện).</p>
<p>Vậy giá mỗi số điện ở mức thứ nhất là <span id="MathJax-Element-41-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>450</mn></math>"><span id="MJXc-Node-331" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-332" class="mjx-mrow"><span id="MJXc-Node-333" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R">450</span></span></span></span></span> đồng.</p>
Hướng dẫn Giải Bài 56 (Trang 34, SGK Toán 8, Tập 2, Phần Đại Số)
GV: 
GV colearn
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