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[不等式] 请问不等式是否成立?

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lemondian posted 2021-11-3 09:08 |Read mode
已知$a^n\leqslant m(a\geqslant 0,m,n\inN^*,且m\geqslant n\geqslant 2)$,则不等式$a^{n-1}\leqslant \frac{3n}{2}$是否成立?

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kuing posted 2021-11-3 14:38
你是为了证明啥问题而提出这个?
这明显不成立,如 n=2, m=10000, a=100

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original poster lemondian posted 2021-11-3 15:08
回复 2# kuing
我弄错了

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isee posted 2021-11-3 15:24
回复 2# kuing

我写了小半,然后删了,发现多半不成立,但又不想找反例~~

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kuing posted 2021-11-3 17:34
回复 4# isee

这么明显都看不出吗
条件式:a ≤ m^(1/n)
待证式:a ≤ 与 m 无关的东西
而且 m 无上限,一看就不成立,反例让 m 超大就行。

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isee posted 2021-11-3 17:52
回复 5# kuing


嗯,没意识到,我只是让 m=100,n=2, 咦”充分条件,必要条件“都要来了,就闪了

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