Question

The nth term of a parallel series is an = 5 6n. Find the sum of the terms of the first of this series.​

Answer 1

Answer:

We have the sum of n terms as: 5⋅n2+2⋅n

We need to find the nth term. We know that:

nthterm= Sum upto n terms − Sum upto n-1 terms

Thus,

nth term =5⋅n2+2⋅n−5⋅(n−1)2−2⋅(n−1)

=5⋅(n2−n2+2n−1)+2⋅(n−(n−1))

=5⋅(2n−1)+2

=10n−3.

And there you have it: nth term =10n−3.

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