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Problems in Mathematical Analysis.pdf - pwp.net.ipl.pt

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74 Differentiation of Functions [Ch. 2<br />

In the follow<strong>in</strong>g examples f<strong>in</strong>d the differentials of the functions<br />

def<strong>in</strong>ed implicitly.<br />

732.<br />

733.<br />

734.<br />

=<br />

735. F<strong>in</strong>d dy at the po<strong>in</strong>t (1,2), if y'y = 6x*.<br />

736. F<strong>in</strong>d the approximate value of s<strong>in</strong> 31.<br />

X<br />

Solution. Putt<strong>in</strong>g * = arc30=-jr- and Ax = arc 1=^, from formula (1)<br />

(see 3) we have s<strong>in</strong> 31=^ s<strong>in</strong> 30 + ^~ cos 30=0.500+0.017-J~^=0.515.<br />

737. Replac<strong>in</strong>g the <strong>in</strong>crement of the function by the differen-<br />

tial, calculate approximately:<br />

a) cos 61; d) In 0.9;<br />

b) tan 44; e) arc tan 1.05.<br />

c) e*\<br />

738. What will be the approximate <strong>in</strong>crease <strong>in</strong> the volume of<br />

a sphere if its radius # = 15 cm <strong>in</strong>creases by 2 mm?<br />

739. Derive the approximate formula (for \&x\ that are small<br />

compared to x)<br />

Us<strong>in</strong>g it, approximate V 5 , Y\7, /70, /640.<br />

740. Derive the approximate formula<br />

and f<strong>in</strong>d approximate values for j!/TO, j/70, jI/200.<br />

741. Approximate the functions:<br />

__<br />

for *=1.03;<br />

for * = 0.2;<br />

c) /(x)- !/"}= for * = 0.1;<br />

l<br />

d) y = ~ x *<br />

e<br />

for x =1.05.<br />

742. Approximate tan 453 /<br />

20".<br />

743. F<strong>in</strong>d the approximate value of arc s<strong>in</strong> 0.54.<br />

744. Approximate \<br />

A*

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