※ 引述《chihhungw (衝浪 八呎板)》之銘言：
: y^-x^/(x^+y^)^
: 對y積分
: 答案是-y/x^+y^ +g(x)
: 感激不盡
∫(y^2 - x^2)dy/(x^2+y^2)^2
y/x = u
= (1/x)∫(u^2-1)du/(u^2+1)^2
= (1/x)∫(1-u^(-2))du/(u+u^(-1))^2
k = u + 1/u
= (1/x) [-u/(u^2+1)]
= (x) [-y/x/(y^2+x^2)]
= -y/(y^2+x^2)
再加上積分常數 g(x)即可
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