等差数列a4+a8=16 则S11=

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等差数列a4+a8=16则S11=等差数列a4+a8=16则S11= 等差数列a4+a8=16则S11=S11=(a1+a11)*11÷2=(a1+a1+10d)*11÷2a4+a8=a1+

等差数列a4+a8=16 则S11=
等差数列a4+a8=16 则S11=
 

等差数列a4+a8=16 则S11=
S11=(a1+a11)*11÷2
=(a1+a1+10d)*11÷2
a4+a8
=a1+3d+a1+7d
=2a1+10d=16
所以S11=16*11÷2
=8*11
=88