"The sums of `n`  terms of three arithmetical progressions are `S_1, S_2`and `S_3dot`
Channel: Doubtnut
Date: 2020-07-05

"The sums of `n`  terms of three arithmetical progressions are `S_1, S_2`and `S_3dot`  The first term of each unity and the common differences are `1,2` and `3`  respectively. Prove that `S_1+S_3=2S_2dot`"