回复：借地儿问道题

来源: 布衣之才 于 2010-12-16 11:41:59 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (256 bytes)
回答: 借地儿问道题 由 3845 于 2010-12-16 04:07:21

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)

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• 妙,但不用广义积分法,可能要扣分. -jinjing- ♀ 给 jinjing 发送悄悄话 (0 bytes) () 12/16/2010 postreply 15:36:59

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