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If a1,a2,a3,……..an, a(n+1),…….. be A.P. ...

If `a_1,a_2,a_3,……..a_n, a_(n+1),……..` be A.P. whose common difference is d and `S_1=a_1+a_2+……..+a_n, S_2=a_(n+1)+………..+a_(2n), S_3=a_(2n+1)+…………+a_(3n)` etc show that `S_1,S_2,S_3, S_4…………` are in A.P. whose common difference is `n^2d`.

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