求lim为2的n次方+3的n次方分之2的n+1次方+3的n+1次方=3,求极限

题目

求lim为2的n次方+3的n次方分之2的n+1次方+3的n+1次方=3,求极限

答案

上下除以3^n
=lim[(2/3)^n+1]/[2*(2/3)^n+3]
(2/3)^n趋于0
所以原式=(0+1)/(0+3)=1/3