Re: [積分] 台大91C
※ 引述《linda1218 (linda)》之銘言:
: sqr2
: S x(sqr(4-x^4))dx =?
: 0
aqr2
(1/2)S (sqr(4-x^4))d(x^2) ( set u=x^2 )
0
2
= (1/2) S sqr(4-u^2) du (set u=2sina, du=2cosada)
0
pi/2
= (1/2) S 4(cosa)^2 da (by wallis formula)
0
= 2 (1/2)(pi/2) = pi/2
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04/29 20:57, , 1F
04/29 20:57, 1F
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