Hướng dẫn giải Hoạt động 4 (Trang 159 SGK Toán Đại số & Giải tích 11)
<p><strong class="content_question">Đề bài</strong></p>
<p>Áp dụng các công thức trong Định lí 3, hãy tính đạo hàm của các hàm số <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><mn>5</mn><msup><mi>x</mi><mn>3</mn></msup><mo>-</mo><mn>2</mn><msup><mi>x</mi><mn>5</mn></msup></math>; <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><mo>-</mo><msup><mi>x</mi><mn>3</mn></msup><msqrt><mi>x</mi></msqrt></math>.</p>
<p class="content_method_header"><strong class="content_method">Phương pháp giải</strong></p>
<div class="content_method_content">
<p>Sử dụng các công thức tính đạo hàm hàm <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><msup><mi>x</mi><mi>n</mi></msup></math> và hàm <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>y</mi><mo>=</mo><msqrt><mi>x</mi></msqrt></math></p>
</div>
<p><strong class="content_detail">Lời giải chi tiết</strong></p>
<p><math xmlns="http://www.w3.org/1998/Math/MathML"><mfenced><mn>1</mn></mfenced><mo> </mo><mo> </mo><mi>y</mi><mo>'</mo><mo>=</mo><mfenced><mrow><mn>5</mn><msup><mi>x</mi><mn>3</mn></msup><mo>-</mo><mn>2</mn><msup><mi>x</mi><mn>5</mn></msup></mrow></mfenced><mo>'</mo><mo>=</mo><mfenced><mrow><mn>5</mn><msup><mi>x</mi><mn>3</mn></msup></mrow></mfenced><mo>'</mo><mo>-</mo><mfenced><mrow><mn>2</mn><msup><mi>x</mi><mn>5</mn></msup></mrow></mfenced><mo>'</mo><mspace linebreak="newline"/><mo>=</mo><mfenced><mrow><mn>5</mn><mo>'</mo><mo>.</mo><msup><mi>x</mi><mn>3</mn></msup><mo>+</mo><mn>5</mn><mo>(</mo><msup><mi>x</mi><mn>3</mn></msup><mo>)</mo><mo>'</mo></mrow></mfenced><mo>-</mo><mfenced><mrow><mn>2</mn><mo>'</mo><mo>.</mo><msup><mi>x</mi><mn>5</mn></msup><mo>+</mo><mn>2</mn><mo>(</mo><msup><mi>x</mi><mn>5</mn></msup><mo>)</mo><mo>'</mo></mrow></mfenced><mspace linebreak="newline"/><mo>=</mo><mfenced><mrow><mn>0</mn><mo>.</mo><msup><mi>x</mi><mn>3</mn></msup><mo>+</mo><mn>5</mn><mo>.</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup></mrow></mfenced><mo>-</mo><mfenced><mrow><mn>0</mn><mo>.</mo><msup><mi>x</mi><mn>5</mn></msup><mo>+</mo><mn>2</mn><mo>.</mo><mn>5</mn><msup><mi>x</mi><mn>4</mn></msup></mrow></mfenced><mspace linebreak="newline"/><mo>=</mo><mfenced><mrow><mn>0</mn><mo>+</mo><mn>15</mn><msup><mi>x</mi><mn>2</mn></msup></mrow></mfenced><mo>-</mo><mfenced><mrow><mn>0</mn><mo>+</mo><mn>10</mn><msup><mi>x</mi><mn>4</mn></msup></mrow></mfenced><mspace linebreak="newline"/><mo>=</mo><mn>15</mn><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mn>10</mn><msup><mi>x</mi><mn>4</mn></msup></math></p>
<p><math xmlns="http://www.w3.org/1998/Math/MathML"><mfenced><mn>2</mn></mfenced><mo> </mo><mo> </mo><mi>y</mi><mo>'</mo><mo>=</mo><mfenced><mrow><mo>-</mo><msup><mi>x</mi><mn>3</mn></msup><msqrt><mi>x</mi></msqrt></mrow></mfenced><mo>'</mo><mspace linebreak="newline"/><mo>=</mo><mfenced><mrow><mo>-</mo><msup><mi>x</mi><mn>3</mn></msup></mrow></mfenced><mo>'</mo><mo>.</mo><msqrt><mi>x</mi></msqrt><mo>+</mo><mfenced><mrow><mo>-</mo><msup><mi>x</mi><mn>3</mn></msup></mrow></mfenced><mo>.</mo><mfenced><msqrt><mi>x</mi></msqrt></mfenced><mo>'</mo><mspace linebreak="newline"/><mo>=</mo><mo>-</mo><mn>3</mn><msup><mi>x</mi><mn>2</mn></msup><mo>.</mo><msqrt><mi>x</mi></msqrt><mo>-</mo><msup><mi>x</mi><mn>3</mn></msup><mo>.</mo><mfrac><mn>1</mn><mrow><mn>2</mn><msqrt><mi>x</mi></msqrt></mrow></mfrac></math></p>