微积分I(标准路径) · free preview

§1.8 The tangent line approximation (continued)

可导函数 $y = f(x)$ 在点 $(a,f(a))$ 处的一般切线近似公式是什么?

1. Exercises (continued)

Exercises (continued)

2. Summary

Summary

3. Reading a linearization

A function pp has local linearization L(x)=−2x+5L(x) = -2x + 5 at a=3a = 3. What are p(3)p(3) and p′(3)p'(3)?

4. Curvature and approximation quality

Near x=3x = 3, a shared tangent line LL approximates ff and gg, where f′′(3)=0.2f''(3) = 0.2 and g′′(3)=−1g''(3) = -1. Why does LL approximate ff better?

5. Estimating position from motion data

An object has position s(9)=4s(9) = 4 feet and velocity s′(9)=−1.2s'(9) = -1.2 feet per second at t=9t = 9 seconds. The tangent line estimate of s(9.34)s(9.34) is

6. A potato temperature forecast

A potato satisfies F(30)=167.6F(30) = 167.6 degrees and F′(30)≈2.065F'(30) \approx 2.065 degrees per minute. Use the tangent line at 3030 to estimate F(33)F(33), rounded to three decimals.

7. Estimating with a declining linear model

With local linearization L(x)=−2x+5L(x) = -2x + 5 at a=3a = 3, estimate p(2.79)p(2.79), rounded to two decimals.

8. Concavity decides the error direction

If p′′(x)<0p''(x) \lt 0 for x<3x \lt 3 and LL is the linearization of pp at 33, then L(2.79)L(2.79) overestimates p(2.79)p(2.79).

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