微积分I(标准路径) · free preview

§1.3 The derivative of a function at a point (continued)

函数在给定区间上的平均变化率是如何定义的?这个量度量的是什么?

1. Summary

Summary

2. Total change versus average rate

China's population is modeled by P(t)=1.15(1.014)tP(t) = 1.15(1.014)^t billion people with tt years since the start of 1993. What is the average rate of change of the population over [0,7][0, 7]?

3. Central difference estimate

A function satisfies f(1)=2.5f(1) = 2.5, f(2)=3.25f(2) = 3.25, and f(3)=3.625f(3) = 3.625. Using a central difference at a=2a = 2, the estimate of f′(2)f'(2) is

4. Which slope answers which question

For a position function ss, which quantity gives the average velocity over the interval [a,b][a, b]?

5. Total population change

With P(t)=1.15(1.014)tP(t) = 1.15(1.014)^t billion people, compute the total change in population between the start of 1993 and the start of 2000. Give your answer in billions of people, rounded to four decimal places.

6. Growth rate in the later decades

The same model P(t)=1.15(1.014)tP(t) = 1.15(1.014)^t gives an average growth rate of about 0.022340.02234 billion people per year over the decade from t=19t = 19 to t=29t = 29. Over how many years was that average computed?

7. Definition of the derivative at zero

For P(t)=1.15(1.014)tP(t) = 1.15(1.014)^t, the instantaneous growth rate at the start of 1993 is P′(0)=lim⁡h→0P(h)−P(0)hP'(0) = \displaystyle\lim_{h \to 0} \frac{P(h) - P(0)}{h}.

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