Bài 3. Đạo hàm của hàm số lượng giác
Hướng dẫn giải Bài 8 (Trang 169 SGK Toán Đại số & Giải tích 11)
<p>Giải bất phương tr&igrave;nh f'(x)&gt;g'(x) biết rằng</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mo>,</mo><mo>&#160;</mo><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><msup><mi>x</mi><mn>3</mn></msup><mo>+</mo><mi>x</mi><mo>-</mo><msqrt><mn>2</mn></msqrt><mo>,</mo><mo>&#160;</mo><mi>g</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>x</mi><mo>+</mo><msqrt><mn>2</mn></msqrt><mspace linebreak="newline"/><mi>b</mi><mo>,</mo><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>2</mn><msup><mi>x</mi><mn>3</mn></msup><mo>-</mo><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><msqrt><mn>3</mn></msqrt><mo>,</mo><mo>&#160;</mo><mi>g</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><msup><mi>x</mi><mn>3</mn></msup><mo>+</mo><mfrac><msup><mi>x</mi><mn>2</mn></msup><mn>2</mn></mfrac><mo>-</mo><msqrt><mn>3</mn></msqrt><mspace linebreak="newline"/><mi>G</mi><mi>i</mi><mi>&#7843;</mi><mi>i</mi><mo>&#160;</mo><mspace linebreak="newline"/><mi>a</mi><mo>,</mo><mo>&#160;</mo><mi>T</mi><mi>a</mi><mo>&#160;</mo><mi>c</mi><mi>&#243;</mi><mo>&#160;</mo><mi>f</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>1</mn><mo>;</mo><mo>&#160;</mo><mi>g</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>6</mn><mi>x</mi><mo>+</mo><mn>1</mn><mspace linebreak="newline"/><mi>f</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>&#62;</mo><mi>g</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>&#8660;</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>1</mn><mo>&#62;</mo><mn>6</mn><mi>x</mi><mo>+</mo><mn>1</mn><mo>&#160;</mo><mo>&#8660;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>2</mn><mi>x</mi><mo>&#62;</mo><mn>0</mn><mo>&#8660;</mo><mfenced open="[" close="]"><mtable><mtr><mtd><mi>x</mi><mo>&#60;</mo><mn>0</mn></mtd></mtr><mtr><mtd><mi>x</mi><mo>&#62;</mo><mn>2</mn></mtd></mtr></mtable></mfenced><mspace linebreak="newline"/><mi>T</mi><mi>&#7853;</mi><mi>p</mi><mo>&#160;</mo><mi>n</mi><mi>g</mi><mi>h</mi><mi>i</mi><mi>&#7879;</mi><mi>m</mi><mo>&#160;</mo><mi>l</mi><mi>&#224;</mi><mo>&#160;</mo><mi>S</mi><mo>&#160;</mo><mo>=</mo><mfenced><mrow><mo>-</mo><mo>&#8734;</mo><mo>;</mo><mn>0</mn></mrow></mfenced><mo>&#8746;</mo><mfenced><mrow><mn>2</mn><mo>;</mo><mo>+</mo><mo>&#8734;</mo></mrow></mfenced><mspace linebreak="newline"/><mi>b</mi><mo>,</mo><mo>&#160;</mo><mi>f</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>6</mn><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>2</mn><mi>x</mi><mo>,</mo><mo>&#160;</mo><mi>g</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>x</mi><mspace linebreak="newline"/><mi>T</mi><mi>a</mi><mo>&#160;</mo><mi>c</mi><mi>&#243;</mi><mo>&#160;</mo><mi>f</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>&#62;</mo><mi>g</mi><mo>'</mo><mfenced><mi>x</mi></mfenced><mo>&#8660;</mo><mn>6</mn><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>2</mn><mi>x</mi><mo>&#62;</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>x</mi><mo>&#8660;</mo><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mi>x</mi><mo>&#62;</mo><mn>0</mn><mo>&#160;</mo><mfenced open="[" close="]"><mtable><mtr><mtd><mi>x</mi><mo>&#60;</mo><mn>0</mn></mtd></mtr><mtr><mtd><mi>x</mi><mo>&#62;</mo><mn>1</mn></mtd></mtr></mtable></mfenced><mspace linebreak="newline"/><mi>V</mi><mi>&#7853;</mi><mi>y</mi><mo>&#160;</mo><mi>S</mi><mo>=</mo><mfenced><mrow><mo>-</mo><mo>&#8734;</mo><mo>;</mo><mn>0</mn></mrow></mfenced><mo>&#8746;</mo><mfenced><mrow><mn>1</mn><mo>;</mo><mo>+</mo><mo>&#8734;</mo></mrow></mfenced></math></p> <p>&nbsp;</p>
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