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问题: 求带有根号的极限

解答:

lim<n→∞>(2^n+3^n+5^n)^(1/n)
=lim<n→∞>{(5^n)*[1+(2^n+3^n/5^n)]}^(1/n)
=5*lim<n→∞>[1+(2^n+3^n/5^n)]^(1/n)
=5*lim<n→∞>{[1+(2^n+3^n/5^n)]^(5^n/2^n+3^n)}^(2^n+3^n/5^n)^(1/n)
=5*lim<n→∞>e^[(2^n+3^n)/(n*5^n)]
=5*e^[lim<n→∞>(2^n*ln2+3^n*ln3)/(5^n+n*5^n*ln5)]
=5*e^0
=5*1
=5