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

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

If the r^(th) term of a series is 1+x+x^(2)+......+x^(r-1), then the sum of the first n terms is

If |r|<1, then the sum of infinite terms of G.P is

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 rth term of a G.P. is (-1)^(r-1).2^(r+1) , state the value of its 4th term :

The mean of r numbers of terms of a series is bary. If the sum of 1st (r - 1) terms is R, then the rth term will be

If the r^(th) term of a series is 1 + x + x^2 + .......+ x^(r-1) , then the sum of the first n terms is

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

If (r+1)^(th) term is (3.5...(2r-1))/(r!) (1/5)^(r) , then this is the term of binomial expansion-