问题
选择题
若Sn是等差数列{an}的前n项和,a2+a10=4,则S11的值为( )
A.12
B.18
C.22
D.44
答案
∵Sn是等差数列{an}的前n项和,a2+a10=4,
∴S11 =
=11(a1+a11) 2
=22,11(a2+a10) 2
故选C.
若Sn是等差数列{an}的前n项和,a2+a10=4,则S11的值为( )
A.12
B.18
C.22
D.44
∵Sn是等差数列{an}的前n项和,a2+a10=4,
∴S11 =
=11(a1+a11) 2
=22,11(a2+a10) 2
故选C.