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设等差数列{an}的前n项和为Sn,若a2+a8=15-a5,则S9的值为( )...
设等差数列{an}的前n项和为Sn,若a2+a8=15-a5,则S9的值为( )
A.60
B.45
C.36
D.18
考点分析:
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