lim[4-2^(n+1)/2^n+2^(n+2)],n→∝

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lim[4-2^(n+1)/2^n+2^(n+2)],n→∝lim[4-2^(n+1)/2^n+2^(n+2)],n→∝lim[4-2^(n+1)/2^n+2^(n+2)],n→∝答:分子分母同除以2

lim[4-2^(n+1)/2^n+2^(n+2)],n→∝
lim[4-2^(n+1)/2^n+2^(n+2)],n→∝

lim[4-2^(n+1)/2^n+2^(n+2)],n→∝
答:分子分母同除以2^(n+2),得到式子【4/2^(n+2)-1/2】/(1/4+1),当n→∝时,分子等于-1/2,分母等于5/4,所以结果是(-1/2)/(5/4)=-2/5.

lim[4-2^(n+1)/2^n+2^(n+2)],
=lim[4-2*2^n/2^n+4*2^n]
=-2/5