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

If the sum of the 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.

If the nth term of a series be (2.3^(n-1) + 1) , find the sum of first 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 nth term of a series is 3^(n)+2n; find the sum of first n 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 sum of first r terms of a series is ar^(2) + br , find the first and 12th 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?

Find the sum of the first n-terms of the series. 2+22+222+…..

If r^(th) term of a series is (2r+1)2^(-r) then sum of its infinite terms is