Question

求极限题，过程要详细

Answer 1

lim(n->∞) [ 3 - (2n+3)/2^n ]
=3- lim(n->∞) (2n+3)/2^n
=3-0
=3

追问

为什么2n+3/2^n极限是0

追答

lim(x->∞) (2x+3)/2^x (∞/∞ 分子分母分别求导)
=im(x->∞) 2/[(ln2).2^x]
=0
=> lim(n->∞) (2n+3)/2^n =0