This is also a great solution....

来源: 乱弹 于 2008-04-02 20:33:22 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (80 bytes)
回答: 回复：Another method 由 yma16 于 2008-04-01 20:11:01

I guess you want to show that f(x) has a real root if and only if f(-1) &le 0.

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