Question

10. The nth term of the series whose sum to n terms is 5n²+ 2n is
(a) 3n-10
(b) 10n - 2
(c) 10n - 3​

Answer 1

Answer:

Step-by-step explanation:

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.  

Thanks for reading!

Answer 2

Answer:

Option (c) is correct.

EXPLANATION ATTACHED