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

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

The nth term of a series is 3^(n) + 2n , find the sum of first n terms of the series.

The rth term of a series is (2r + 1)2^(r ) , find the sum of first n terms of the series.

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

The nth term of a series is 3^(n)+2n; find the sum of first n 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 sum of first r terms of a series is ar^(2) + br , find the first and 12th terms of the series.

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

Find n^(th) term of the series 1+(1+2)+(1+2+3)+.... Find the sum to n terms of the series

If the sum of n tems of a series be 5n^2+3n , find its nth term. Are the terms of this series in A.P.?