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Thomas Calculus 13th [Solutions]

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Chapter 7 Practice Exercises 537<br />

(d)<br />

(e)<br />

1 1<br />

x<br />

1<br />

x<br />

2<br />

1 1<br />

x<br />

x<br />

1 x<br />

2<br />

1<br />

1 2<br />

1<br />

1<br />

x<br />

x<br />

x<br />

2<br />

lim<br />

tan<br />

tan<br />

lim lim lim 1<br />

x x x x<br />

x<br />

2<br />

1 1 1<br />

2<br />

1 1 sin x<br />

1 x<br />

x<br />

x<br />

2 3<br />

1<br />

x<br />

2x<br />

2 1<br />

1<br />

2<br />

x<br />

2<br />

x<br />

lim<br />

sin<br />

lim lim lim<br />

x x x x<br />

same rate<br />

faster<br />

(f )<br />

x<br />

e<br />

x<br />

2<br />

e<br />

x<br />

x x x x x<br />

2x<br />

sech<br />

lim lim lim 2 lim 2 2<br />

x e x e x e e e x 1 e<br />

same rate<br />

21. (a)<br />

(b)<br />

1 1<br />

x<br />

2<br />

x<br />

4<br />

1<br />

x<br />

2<br />

1 1<br />

x<br />

2<br />

x<br />

4<br />

1<br />

x<br />

4<br />

1 1 2 for x sufficiently large true<br />

2<br />

x<br />

2<br />

x 1 M for any positive integer M whenever x M false<br />

(c) lim x lim 1 1<br />

ln 1<br />

x<br />

x x<br />

x 1<br />

(d)<br />

(e)<br />

(f )<br />

x<br />

1/ x<br />

ln x<br />

lim ln(ln x) 1<br />

ln x<br />

lim lim ln x<br />

0<br />

x x x<br />

1<br />

1<br />

x<br />

the same growth rate false<br />

tan x for all x true<br />

1 2<br />

cosh x 1 2x<br />

1 e<br />

1 (1 1) 1 if x 0 true<br />

x<br />

e 2 2<br />

grows slower true<br />

22. (a)<br />

1<br />

x<br />

4<br />

1 1<br />

x<br />

2<br />

x<br />

4<br />

1<br />

2<br />

x 1<br />

1<br />

if x 0 true<br />

(b)<br />

1<br />

x<br />

4<br />

lim lim 1 0<br />

2<br />

x<br />

x x 1<br />

1 1<br />

x<br />

2<br />

x<br />

4<br />

1<br />

x<br />

(c) lim ln x lim 0<br />

x<br />

x 1<br />

x<br />

1<br />

(d) ln 2x<br />

ln 2 1 1 1 2<br />

ln x ln x<br />

(e)<br />

(f )<br />

true<br />

true<br />

if x 2 true<br />

1 1<br />

1 cos<br />

x x 2<br />

if 1<br />

sec<br />

1 1 1 2<br />

x true<br />

sinh x 1 2x<br />

1 e<br />

1 if x 0 true<br />

x<br />

e 2 2<br />

23.<br />

1 1<br />

1<br />

df x<br />

df x df 1 df<br />

e<br />

1 1 1<br />

dx dx dx 1 2 1 3<br />

x f (ln 2) x f (ln 2) e<br />

dx<br />

x ln 2<br />

x ln 2<br />

Copyright<br />

2014 Pearson Education, Inc.

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