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Exercicios resolvidos James Stewart vol. 2 7ª ed - ingles

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208 D CHAPTER 14 PARTIAL DERIVATIVES<br />

5. w=xevl =, x = t2, y = l-t, z=1+2t =><br />

dw = OW dx + ow dy + ow dz = ey/ z. 2t + xevl= (.!) .(- 1) + xeYI= (-J!...) . 2 = evl= (2t - ~ - 2xy)<br />

dt ox dt /Jy dt oz dt z z 2 z z2<br />

7. z = x 2 y 3 , x = scost, y = ssint =><br />

az oz ax oz 8y 3 2 2 •<br />

!i"'" = !i"'"' + -a -a = 2xy cost+ 3x y sm t<br />

us uxus y s .<br />

az . 8z Ox az 8y 3 . 2 2 s . 2<br />

ot = ox at+ oy at = (2xy )(- ssmt) + (3x y )(scost) = -2sxy smt + 3sx 2 y cost<br />

9. z = sin() cos, () = st 2 , ¢ = s 2 t =><br />

~; = ~; ~~ + ~~ ~! =(cos 8 cos q))(t~) + (- sinO sin q.,)(2st) = t 2 cosO cos¢ - 2stsin0 sin )(2st) + (-sinO sin )(s 2 ) = 2stcos0 cos¢- s 2 sinO sin

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