Q1 of 105 Page 146

Find the sum of the following APs:

2, 7, 12, …., to 10 terms.

In the above series

First term (a) = 2


Common different (d) = n2 – n1 = 7 – 2 = 5


No. Of terms (n) = 10


The sum of the series is given by Sn = [ 2a + (n-1) d]


= [ 2×2 + (10-1)5]


= 245


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