Bài 4: Bất Phương Trình Bậc Nhất Một Ẩn
Hướng dẫn giải Bài 23 (Trang 47 SGK Toán Đại số 8, Tập 2)
<p>Giải c&aacute;c bất phương tr&igrave;nh v&agrave; biểu diễn tập nghiệm tr&ecirc;n trục số:</p> <p>a) 2x-3 &gt; 0<span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span>b) 3x+4 &lt;0</p> <p>c) 4-3x&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&#8804;</mo></math>0<span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span>d) 5-2x<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&#8805;</mo></math>0</p> <p><em><strong>Hướng dẫn:</strong></em></p> <p>a)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><mi>x</mi><mo>-</mo><mn>3</mn><mo>&#62;</mo><mn>0</mn><mo>&#8660;</mo><mn>2</mn><mi>x</mi><mo>&#62;</mo><mn>3</mn><mo>&#8660;</mo><mi>x</mi><mo>&#62;</mo><mfrac><mn>3</mn><mn>2</mn></mfrac></math><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/12032022/screenshot-2022-03-12-095352-mnYQE6.png" /></p> <p>b)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn><mi>x</mi><mo>+</mo><mn>4</mn><mo>&#60;</mo><mn>0</mn><mo>&#8660;</mo><mn>3</mn><mi>x</mi><mo>&#60;</mo><mo>-</mo><mn>4</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mfrac><mrow><mo>-</mo><mn>4</mn></mrow><mn>3</mn></mfrac></math><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/12032022/screenshot-2022-03-12-095514-MpcDRF.png" /></p> <p>c)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>4</mn><mo>-</mo><mn>3</mn><mi>x</mi><mo>&#8804;</mo><mn>0</mn><mo>&#8660;</mo><mo>-</mo><mn>3</mn><mi>x</mi><mo>&#8804;</mo><mo>-</mo><mn>4</mn><mo>&#8660;</mo><mi>x</mi><mo>&#8805;</mo><mfrac><mn>4</mn><mn>3</mn></mfrac></math><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/12032022/screenshot-2022-03-12-095623-D1G0sj.png" /></p> <p>d)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>5</mn><mo>-</mo><mn>2</mn><mi>x</mi><mo>&#8805;</mo><mn>0</mn><mo>&#8660;</mo><mo>-</mo><mn>2</mn><mi>x</mi><mo>&#8805;</mo><mo>-</mo><mn>5</mn><mo>&#8660;</mo><mi>x</mi><mo>&#8804;</mo><mfrac><mn>5</mn><mn>2</mn></mfrac></math><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><span class="mce-nbsp-wrap" contenteditable="false">&nbsp;&nbsp;&nbsp;</span><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/12032022/screenshot-2022-03-12-095742-4hvzTV.png" /></p>
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