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=A.4 B.2 C.-2 D.-4

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$等差数列{an}的前n项和为Sn,若lim n→∞ Sn/n^2=2,则该数列的公差d=A.4 B.2 C.-2 D.-4$

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=A.4 B.2 C.-2 D.-4
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=
A.4 B.2 C.-2 D.-4

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=A.4 B.2 C.-2 D.-4
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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