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Thomas Calculus 13th [Solutions]

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218 Chapter 3 Derivatives<br />

k k k<br />

k dx dx<br />

k 1<br />

k du d v u d v .<br />

dx dx<br />

k dx<br />

k 1<br />

Therefore the formula (c) holds for n ( k 1) whenever it holds for n k.<br />

k k 1 k 1 k<br />

1<br />

k 1 2<br />

du d v d v d u<br />

1 ( 1) d u dv d u d v<br />

k u v k<br />

1 1 2<br />

...<br />

k k k k k 1 2<br />

dx dx dk dx dx dx<br />

k k 1<br />

27. (a)<br />

(b)<br />

2 2 2<br />

2<br />

2<br />

4<br />

T g (1sec )(32.2 ft/sec )<br />

T L L L L<br />

g<br />

2 2<br />

4 4<br />

2<br />

0.8156ft<br />

2<br />

T 4 L T 2 L; dT 2 1 dL dL; dT<br />

(0.01 ft) 0.00613 sec.<br />

g g g L Lg<br />

2 2<br />

(0.8156ft)(32.2ft/sec )<br />

(c) Since there are 86,400 sec in a day, we have we have (0.00613 sec)(86, 400 sec/day)<br />

8.83 min/day; the clock will lose about 8.83 min/day.<br />

529.6 sec/day, or<br />

28.<br />

3 2 2<br />

v s dv 3 s ds k (6 s ) ds 2 k . If s<br />

dt dt dt<br />

0 the initial length of the cubes side, then s 1 s 0 2k<br />

2k s 0 s 1 . Let t the time it will take the ice cube to melt. Now, 1/3<br />

s0 s0 ( v0<br />

)<br />

t<br />

2k s 1/3<br />

1/3<br />

0 s1<br />

3<br />

( v0 ) v<br />

4 0<br />

1 11 hr.<br />

1/3<br />

1<br />

3<br />

4<br />

Copyright<br />

2014 Pearson Education, Inc.

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