已知Sn为等差数列an的前n项和,a6=100,则S11=
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已知Sn为等差数列an的前n项和,a6=100,则S11=
![已知Sn为等差数列an的前n项和,a6=100,则S11=](/uploads/image/z/18222229-37-9.jpg?t=%E5%B7%B2%E7%9F%A5Sn%E4%B8%BA%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97an%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%2Ca6%3D100%2C%E5%88%99S11%3D)
S11
= (a1 + a11) × 11 ÷ 2
= 2a6 × 11 ÷ 2
= 11a6
= 11 × 100
= 1100
= (a1 + a11) × 11 ÷ 2
= 2a6 × 11 ÷ 2
= 11a6
= 11 × 100
= 1100
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