# Doubt from summation of series

**Tanmay_1**#1

**rupesh_2020**#3

Tonmoy ji kindly tell me from where you have given this problems, if this is possible for you. Today I taught my student same topic and want to include these some in my DPP.

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**Sajal_2019**#10

For q.28 add and substract 1 from numerators of each term and gerenate difference series and hence answer would be

Sn = 1 - 1/(1+a1)(1+a2).....(1+an)