等差数列{an}中,a3+a10=5,求(1)S12.(2)a2+a11(3)a5+2a6+a6

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等差数列{an}中,a3+a10=5,求(1)S12.(2)a2+a11(3)a5+2a6+a6

等差数列{an}中,a3+a10=5,求(1)S12.(2)a2+a11(3)a5+2a6+a6
等差数列{an}中,a3+a10=5,求(1)S12.(2)a2+a11(3)a5+2a6+a6

等差数列{an}中,a3+a10=5,求(1)S12.(2)a2+a11(3)a5+2a6+a6
1)S12=6(a6+a7)=6(a3+a10)=30
2)a2+a11=a3+a10=5
3)写错了吧?