Calculus Volume 1

Chapter 4 | Applications of Derivatives

467

5

10

15

20

x

x 2

25

100

225

400

e x

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

Table 4.9 Growth rates of a power function and an exponential function.

x 2 =∞, we can use L’Hôpital’s rule to evaluate lim x →∞ ln x x 2 . We

b. Since lim x

→∞ ln

x =∞ and lim x →∞

obtain

1/ x 2 x = lim x →∞

ln x x 2

1 2 x 2

lim x →∞

= lim x →∞

=0.

Thus, x 2 grows more rapidly than ln x as x →∞ (see Figure 4.74 and Table 4.10 ).

Figure 4.74 A power function grows at a faster rate than a logarithmic function.

10,000

10

100

1000

x

ln( x )

6.908

9.210

2.303

4.605

x 2

10,000 1,000,000 100,000,000

100

Table 4.10 Growth rates of a power function and a logarithmic function

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