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§2.5 The chain rule (continued)

什么是复合函数,我们如何在代数上识别其结构?

1. Using multiple rules simultaneously

Using multiple rules simultaneously

2. The composite version of basic function rules

The composite version of basic function rules

3. Summary

Summary

4. An exponential times a fourth power of secant

For h(t)=3t2+2tsec⁡4(t)h(t) = 3^{t^2+2t}\sec^4(t), which combination of rules does the derivative require?

5. A root of a two term inside

For p(r)=4r6+2erp(r) = 4\sqrt{r^6 + 2e^r}, which expression is p′(r)p'(r)?

6. Product of two different compositions

For m(v)=sin⁡(v2)cos⁡(v3)m(v) = \sin(v^2)\cos(v^3), which structure does m′(v)m'(v) have?

7. A cosine of ten y over an exponential sum

For h(y)=cos⁡(10y)e4y+1h(y) = \frac{\cos(10y)}{e^{4y}+1}, which structure does h′(y)h'(y) have?

8. Two to a product power

For s(z)=2z2sec⁡(z)s(z) = 2^{z^2\sec(z)}, which structure does s′(z)s'(z) have?

9. Sine of an exponential of a square

For c(x)=sin⁡(ex2)c(x) = \sin(e^{x^2}), which expression is c′(x)c'(x)?

10. Chain rule from a value table

Suppose f(−1)=2f(-1) = 2, f′(−1)=−5f'(-1) = -5, f(2)=−3f(2) = -3, f′(2)=4f'(2) = 4, g(−1)=−3g(-1) = -3, g′(−1)=4g'(-1) = 4, g(2)=−1g(2) = -1, and g′(2)=2g'(2) = 2. For C(x)=f(g(x))C(x) = f(g(x)), compute C′(2)C'(2).

11. A self composition from a table

With the same table, for D(x)=f(f(x))D(x) = f(f(x)) compute D′(−1)D'(-1), using D′(x)=f′(f(x))⋅f′(x)D'(x) = f'(f(x)) \cdot f'(x).

12. Linear inner functions

For composite functions with linear inside, such as tan⁡(17x)\tan(17x), the chain rule gives

13. Chain rule versions of two basic rules

The chain rule upgrades ddx[sin⁡(x)]=cos⁡(x)\frac{d}{dx}[\sin(x)] = \cos(x) and ddx[ax]=axln⁡(a)\frac{d}{dx}[a^x] = a^x\ln(a) to which general statements?

14. Which composition changes fastest

With f(x)=x3f(x) = x^3 and g(x)=sin⁡(x)g(x) = \sin(x), the derivatives satisfy h′(0.25)≈0.178h'(0.25) \approx 0.178 for h=f(g(x))h = f(g(x)) and r′(0.25)≈0.188r'(0.25) \approx 0.188 for r=g(f(x))r = g(f(x)). Also, which derivative is periodic?

15. Derivative pattern with an unknown inner function

Let uu be differentiable. Which list correctly pairs each function with its derivative?

16. Composition of graphed piecewise linear functions

Piecewise linear pp and qq satisfy q(0)=2q(0) = 2, p′(2)=2p'(2) = 2, q′(0)=0q'(0) = 0, q(3)=0q(3) = 0, p′(0)=12p'(0) = \frac{1}{2}, and q′(3)=−1q'(3) = -1. For C(x)=p(q(x))C(x) = p(q(x)), the values C′(0)C'(0) and C′(3)C'(3) are

17. A composition failing at a corner

With the same graphs, Y(x)=q(q(x))Y(x) = q(q(x)) has no derivative at x=−2x = -2, because q(−2)=−1q(-2) = -1 and qq has a corner at −1-1.

18. Derivative pattern with an exponential inner function

Let uu be differentiable. For q(x)=u(ex)q(x) = u(e^x), which expression is q′(x)q'(x)?

19. Water height driven by time

A spherical tank has V=π3h2(12−h)V = \frac{\pi}{3}h^2(12-h) cubic feet at water height hh feet, and the height follows h(t)=sin⁡(πt)+1h(t) = \sin(\pi t) + 1 feet at tt hours. At t=2t = 2, the height satisfies h(2)=1h(2) = 1 and h′(2)=πh'(2) = \pi. The rate dVdt\frac{dV}{dt} at t=2t = 2 equals

20. Filling rate of a spherical tank

Water volume in a spherical tank is V=π3h2(12−h)V = \frac{\pi}{3}h^2(12-h) cubic feet at height hh feet. Compute dVdh\frac{dV}{dh} at h=1h = 1 rounded to three decimals.

21. Two meanings of a volume rate

In the tank problem, dVdh\frac{dV}{dh} at h=1h = 1 measures volume change per extra foot of height, while dVdt\frac{dV}{dt} at t=2t = 2 measures volume change per extra hour, and the two are linked by the height's own rate of change.

22. Air pressure dropping for a pilot

Air pressure is P=30e−0.0000323hP = 30e^{-0.0000323h} inches of mercury at altitude hh feet. Compute P′(1000)P'(1000) rounded to six decimals.

23. Reading the pressure derivative

The value P′(1000)≈−0.000938P'(1000) \approx -0.000938 inches of mercury per foot means the pressure drops by about that amount for each additional foot of elevation near 10001000 feet.

24. A gentle square root tangent

The tangent line to y=ex+3y = \sqrt{e^x + 3} at x=0x = 0 has slope 14\frac{1}{4}.

25. Particle on a reciprocal power track

A particle has position s(t)=1(t2+1)3s(t) = \frac{1}{(t^2+1)^3} inches at tt seconds. Compute the velocity s′(1)s'(1) as a fraction.

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