※ 引述《LiShaShau (粒瞎小?)》之銘言：
: 問一下괊
: ∫x^3(x^2-4)^1/2dx
3
S x (x^2 - 4)^1/2 dx
1
= --- S x^2(x^2 - 4)^1/2 dx^2
2
Let x^2 = 2secA
then dx^2 = d2secA = 2secAtanA dA
原式......
1 2
= --- S 2secA(2 secA tanA)(4tan A)^1/2 dA
2
2
= S [2sec AtanA][2tanA] dA
2 2
= 4 S sec A tan A dA
2 2
= 4 S tan A d(tan A)
4 3
= --- tan A + c
3
4 (x^4-4)^1/2 3
= ---[----------- ] + c..........
3 2
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