X+X的N次方分之A
=x/n+x/n+...+x/n+a/x^n
≥(n+1) * (n+1)次根号下(x/n)...(x/n)(a/x^n) =n+1
则
(n+1)次根号下(x/n)...(x/n)(a/x^n)
=(n+1)次根号下(a/n^n)=1
a/n^n=1
a=n^n
满意请轻戳此处
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