Ôn tập Chương II
Hướng dẫn Giải bài 13 (Trang 51, SGK Toán 10, Tập 1)
<p>Chọn phương &aacute;n đ&uacute;ng.</p> <p><strong>C&acirc;u hỏi</strong>: Tập x&aacute;c định của h&agrave;m số <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><msqrt><mi>x</mi><mo>-</mo><mn>3</mn></msqrt><mo>-</mo><msqrt><mn>1</mn><mo>-</mo><mn>2</mn><mi>x</mi></msqrt></math> l&agrave;:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mo>(</mo><mi>A</mi><mo>)</mo><mo>&#160;</mo><mi>D</mi><mo>=</mo><mfenced open="[" close="]"><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac><mo>;</mo><mn>3</mn></mrow></mfenced><mo>&#160;</mo><mo>;</mo><mspace linebreak="newline"/><mo>(</mo><mi>B</mi><mo>)</mo><mo>&#160;</mo><mi>D</mi><mo>=</mo><mfenced open="[" close="]"><mrow><mo>-</mo><mo>&#8734;</mo><mo>;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow></mfenced><mo>&#160;</mo><mo>&#8746;</mo><mo>&#160;</mo><mo>[</mo><mn>3</mn><mo>;</mo><mo>+</mo><mo>&#8734;</mo><mo>)</mo><mo>&#160;</mo><mo>;</mo><mspace linebreak="newline"/><mo>(</mo><mi>C</mi><mo>)</mo><mo>&#160;</mo><mi>D</mi><mo>=</mo><mo>&#8709;</mo><mo>&#160;</mo><mo>;</mo><mspace linebreak="newline"/><mo>(</mo><mi>D</mi><mo>)</mo><mo>&#160;</mo><mi>D</mi><mo>=</mo><mi mathvariant="normal">&#8477;</mi></math></p> <p><strong>Hướng dẫn giải:</strong></p> <p>H&agrave;m số&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><msqrt><mi>x</mi><mo>-</mo><mn>3</mn></msqrt><mo>-</mo><msqrt><mn>1</mn><mo>-</mo><mn>2</mn><mi>x</mi></msqrt></math> x&aacute;c định khi&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfenced open="{" close=""><mtable columnalign="left"><mtr><mtd><mi>x</mi><mo>-</mo><mn>3</mn><mo>&#8805;</mo><mn>0</mn></mtd></mtr><mtr><mtd><mn>1</mn><mo>-</mo><mn>2</mn><mi>x</mi><mo>&#8805;</mo><mn>0</mn></mtd></mtr></mtable></mfenced><mo>&#8660;</mo><mfenced open="{" close=""><mtable columnalign="left"><mtr><mtd><mi>x</mi><mo>&#8805;</mo><mn>3</mn></mtd></mtr><mtr><mtd><mi>x</mi><mo>&#8804;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac></mtd></mtr></mtable></mfenced></math></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&#8660;</mo><mo>&#160;</mo><mi>x</mi><mo>&#8712;</mo><mo>(</mo><mo>-</mo><mo>&#8734;</mo><mo>;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mo>]</mo><mo>&#8745;</mo><mo>[</mo><mn>3</mn><mo>;</mo><mo>+</mo><mo>&#8734;</mo><mo>)</mo></math></p> <p>Tuy nhi&ecirc;n&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>(</mo><mo>-</mo><mo>&#8734;</mo><mo>;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mo>]</mo><mo>&#8745;</mo><mo>[</mo><mn>3</mn><mo>;</mo><mo>+</mo><mo>&#8734;</mo><mo>)</mo><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mo>&#8709;</mo></math></p> <p>=&gt; <strong>Đ&aacute;p &aacute;n đ&uacute;ng l&agrave; C</strong></p>
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