Question

Sum of first n terms of an ap sequance is 3n2+5n.what is the sum of its first n+1 terms.find the sum of its first 10 terms.

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Answer 1

a) 3n^2 + 11n + 8

b) 350

Explanation:

10) 3(10^2)+ 5*10 = 350

n+1) 3(n+1)^2 + 5(n+1)

3(n^2 + 2n + 1) + 5n+5

3n^2 + 6n+3 + 5n + 5

3n^2 + 11n + 8