回复：借地儿问道题

来源: 于 2010-12-16 11:41:59 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

1/(x^2 + x - 2) = 1 / [(x-1)(x+2)] = [1/(x-1) - 1/(x+2)]/3 

integral of the above expression is (1/3) * ln [(x-1)/(x+2)]

so the answer is -(1/3) * ln 4

 

(original problem should not have dx twice)