求极限,证明第15题
2017-09-22
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lim (1/n²)ln[f(1)·f(2)·...·f(n)]
n→∞
=lim (1/n²)ln(e¹·e²·...·eⁿ)
n→∞
=lim (1/n²)ln[e^(1+2+...+n)]
n→∞
=lim (1/n²)(1+2+...+n)
n→∞
=lim (1/n²)[½n(n+1)]
n→∞
=lim (n²+n)/(2n²)
n→∞
=lim (1+ 1/n)/2
n→∞
=lim (1/n²)ln(e¹·e²·...·eⁿ)
n→∞
=lim (1/n²)ln[e^(1+2+...+n)]
n→∞
=lim (1/n²)(1+2+...+n)
n→∞
=lim (1/n²)[½n(n+1)]
n→∞
=lim (n²+n)/(2n²)
n→∞
=lim (1+ 1/n)/2
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