已知{an}是公差不為零的等差數(shù)列,如果sn是{an}的前n項(xiàng)的和,那么limn→∞nansn等于_.
已知{a
n}是公差不為零的等差數(shù)列,如果s
n是{a
n}的前n項(xiàng)的和,那么
等于______.
優(yōu)質(zhì)解答
設(shè)a
n=a
1+(n-1)d,s
n=na
1+
d,代入得
=
=
=2
故答案為2
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