The nth term of a series is `3^n + 2n` ; find the sum of first n terms of the series.

If the sum of the first n terms of the series

If the nth term of a series be (2.3^(n-1) + 1) , find the sum of first r terms of the series.

The sum of the first n terms of a series is 31, and the sum of the first n - 1 terms of the series is 20. What is the value of nth terms in the series?

The nth term of an A.P. is 7n-5, find the sum of first 20 terms of the series.

If the sum of n terms of a series is a + bn + cn^2 . Find the nth term and nature of the series.

The nth term of a series in A.P. is an + b. Find the sum of the series up to n terms.

The sum of n terms of a series is 3n^2+5n find the value of n if nth term is 152: