微积分I(标准路径) · free preview

§3.5 Global optimization

求函数的相对极值与求函数的全局极值之间有什么区别?

1. Introduction

Introduction

2. Global Optimization

Global Optimization

3. Let $f(x) = 2 + \fra…$

Let f(x)=2+31+(x+1)2f(x) = 2 + \frac{3}{1+(x+1)^2}.

Find f′(x)f'(x) and use it to determine all of the critical numbers of ff.

4. Find all critical nu…

Find all critical numbers of gg that lie in the interval −2≤x≤3-2 \le x \le 3.

5. Use a graphing utili…

Use a graphing utility to construct the graph of gg on the interval −2≤x≤3-2 \le x \le 3.

6. From the graph

From the graph, determine the xx-values at which the absolute minimum and absolute maximum of gg occur on the interval [−2,3][-2,3].

7. How do your answers …

How do your answers change if we instead consider the interval −2≤x≤2-2 \le x \le 2?

8. What if we instead c…

What if we instead consider the interval −2≤x≤1-2 \le x \le 1?

9. $h(x) = xe^{-x}$

h(x)=xe−xh(x) = xe^{-x}, [0,3][0,3]

10. $p(t) = \sin(t) + \c…$

p(t)=sin⁡(t)+cos⁡(t)p(t) = \sin(t) + \cos(t), [−π2,π2][-\frac{\pi}{2}, \frac{\pi}{2}]

11. $q(x) = \frac{x^2}{x-2}$

q(x)=x2x−2q(x) = \frac{x^2}{x-2}, [3,7][3,7]

12. $f(x) = 4 - e^{-(x-2)^2}$

f(x)=4−e−(x−2)2f(x) = 4 - e^{-(x-2)^2}, (−∞,∞)(-\infty, \infty)

13. $h(x) = xe^{-ax}$

h(x)=xe−axh(x) = xe^{-ax}, [0,2a][0, \frac{2}{a}] (a>0a \gt 0)

14. $f(x) = b - e^{-(x-a)^2}$

f(x)=b−e−(x−a)2f(x) = b - e^{-(x-a)^2}, (−∞,∞)(-\infty, \infty), a,b>0a, b \gt 0

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