微积分I(标准路径) · free preview

§2.3 The product and quotient rules

函数的代数结构如何引导我们使用快捷法则计算其导数?

1. Introduction

Introduction

2. The product rule

The product rule

3. The quotient rule

The quotient rule

4. Find the derivative …

Find the derivative of

f(x)=7x11−4⋅9x+πsin⁡(x)−3cos⁡(x)f(x) = 7x^{11} - 4 \cdot 9^x + \pi \sin(x) - \sqrt{3}\cos(x)

. Because ff is a sum of basic functions, we can now quickly say that f′(x)=77x10−4⋅9xln⁡(9)+πcos⁡(x)+3sin⁡(x)f'(x) = 77x^{10} - 4 \cdot 9^x \ln(9) + \pi \cos(x) + \sqrt{3} \sin(x).

5. Use the product rule…

Use the product rule to differentiate P(z)=z3⋅cos⁡(z)P(z) = z^3 \cdot \cos(z).

6. Use the quotient rul…

Use the quotient rule to differentiate Q(t)=sin⁡(t)2tQ(t) = \dfrac{\sin(t)}{2^t}.

7. Statement of the product rule

If ff and gg are differentiable, the product rule says that the derivative of f(x)⋅g(x)f(x) \cdot g(x) equals

8. Product of an exponential and a sine

Let f(x)=exsin⁡(x)f(x) = e^x \sin(x). Which expression is f′(x)f'(x)?

9. Rational slope at the origin

For R(x)=x2−2x−8x2−9R(x) = \frac{x^2 - 2x - 8}{x^2 - 9}, the slope of the tangent line at x=0x = 0 is

10. Product slope at one

For f(x)=exsin⁡(x)f(x) = e^x \sin(x), compute the tangent slope f′(1)f'(1) rounded to three decimals.

11. Flash intensity rate

A camera flash has intensity I(t)=100tetI(t) = \frac{100t}{e^t} candles with tt in milliseconds. Compute I′(2)I'(2) rounded to three decimals.

12. Quotient rule territory

The quotient rule formula for fg\frac{f}{g} applies at every point where g(x)≠0g(x) \ne 0.

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