等差数列{an}的前n项和为Sn,若lim n→∞ Sn/n^2=2,则该数列的公差d=
1个回答
sn=a1n+n(n-1)d/2
所以
lim n→∞ Sn/n^2
=lim n→∞ 【a1n+n(n-1)d/2】/n^2=d/2=2
所以
d=4
选A
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