Calculus Volume 1

468

Chapter 4 | Applications of Derivatives

4.44 Compare the growth rates of x 100 and 2 x .

Using the same ideas as in Example 4.45 a. it is not difficult to show that e x grows more rapidly than x p for any p >0. In Figure 4.75 and Table 4.11 , we compare e x with x 3 and x 4 as x →∞.

Figure 4.75 The exponential function e x grows faster than x p for any p >0. (a) A comparison of e x with x 3 . (b) A comparison of e x with x 4 .

5

10

15

20

x

x 3

125

1000

3375

8000

x 4

50,625

160,000

625 10,000

e x

148 22,026 3,269,017 485,165,195

Table 4.11 An exponential function grows at a faster rate than any power function Similarly, it is not difficult to show that x p grows more rapidly than ln x for any p >0. In Figure 4.76 and Table4.12 , we compare ln x with x 3 and x .

Figure 4.76 The function y = ln( x ) grows more slowly than x p for any p >0 as x →∞.

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