In an A.P,the sum of m terms of an AP is n and sum of n terms of AP is m,then prove that sum of (m+n) terms of AP is-(m+n)

Explanation

Let a be the first term and d be the common difference of the `A.P`

Then,

`S_m​=n`


`=>m/2​{2a+(m−1)d}=n`

`=>2am+m(m−1)d=2n->(i)`


and, `S_n​=m`

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