[積分] 求助!

[fsshman (翼德)]

                r
∫----------------------------------- dr
   [ r^2 + h^2 - rh*2^(1/2) ]^(1/2)



答案是


[h^2+r^2-rh*2^(1/2)]^(1/2)
+h/2^(1/2)*ln[2(h^2+r^2-rh*2^(1/2))^(1/2)+2r-h*2^(1/2)]


我用代數變換去算(u=r-h/2^(1/2))，可是不知道為甚麼，ln[]的裡面少了兩倍


[h^2+r^2-rh*2^(1/2)]^(1/2)
+h/2^(1/2)*ln[(h^2+r^2-rh*2^(1/2))^(1/2)+r-h/2^(1/2)]

屢試不爽，希望有人為我解惑一下，謝謝!
(跟號2打起來好麻煩= =)

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