Ôn Tập Chương 4
Hướng dẫn giải Bài 40 (Trang 53 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) x-1 &lt; 3<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><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) x+2 &gt; 1</p> <p>c) 0,2x &lt; 0,6<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><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) 4+2x &lt; 5</p> <p><em><strong>Hướng dẫn:</strong></em></p> <p>a)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>x</mi><mo>-</mo><mn>1</mn><mo>&#60;</mo><mn>3</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mn>3</mn><mo>+</mo><mn>1</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mn>4</mn></math></p> <p><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><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/14032022/screenshot-2022-03-14-145324-rtSnIa.png" /></p> <p>b)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>x</mi><mo>+</mo><mn>2</mn><mo>&#62;</mo><mn>1</mn><mo>&#8660;</mo><mi>x</mi><mo>&#62;</mo><mn>1</mn><mo>-</mo><mn>2</mn><mo>&#8660;</mo><mi>x</mi><mo>&#62;</mo><mo>-</mo><mn>1</mn></math></p> <p><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><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/14032022/screenshot-2022-03-14-145359-S7sn0I.png" /></p> <p>c)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>0</mn><mo>,</mo><mn>2</mn><mi>x</mi><mo>&#160;</mo><mo>&#60;</mo><mo>&#160;</mo><mn>0</mn><mo>,</mo><mn>6</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mo>&#160;</mo><mn>0</mn><mo>,</mo><mn>6</mn><mo>:</mo><mn>0</mn><mo>,</mo><mn>2</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mn>3</mn></math></p> <p><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><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/14032022/screenshot-2022-03-14-145432-6jqjam.png" /></p> <p>d)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>4</mn><mo>+</mo><mn>2</mn><mi>x</mi><mo>&#60;</mo><mn>5</mn><mo>&#8660;</mo><mn>2</mn><mi>x</mi><mo>&#60;</mo><mn>5</mn><mo>-</mo><mn>4</mn><mo>&#8660;</mo><mi>x</mi><mo>&#60;</mo><mn>0</mn><mo>,</mo><mn>5</mn></math></p> <p><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><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/14032022/screenshot-2022-03-14-145506-wWmRE9.png" /></p>
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