等差数列前n项和为Sn=1/2(An+1/An),求通项An
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等差数列前n项和为Sn=1/2(An+1/An),求通项An
![等差数列前n项和为Sn=1/2(An+1/An),求通项An](/uploads/image/z/19200207-39-7.jpg?t=%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%E5%89%8Dn%E9%A1%B9%E5%92%8C%E4%B8%BASn%3D1%2F2%28An%2B1%2FAn%29%2C%E6%B1%82%E9%80%9A%E9%A1%B9An)
带入n=1,因为A1=S1,所以可以求出A1
再设n>=2时,Sn-S(n-1)=d,带入就可以求出d
等差数列通项公式An=A1+(n-1)d
PS:你给的题分数线太多看的我有点晕~所以就把方法告诉你了~
再设n>=2时,Sn-S(n-1)=d,带入就可以求出d
等差数列通项公式An=A1+(n-1)d
PS:你给的题分数线太多看的我有点晕~所以就把方法告诉你了~
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