Find n if 1 + 3 + 5 + 7 + …….. Upto n terms = 225.

Find the sum of the series – 1 + 5 + 11 +….to n terms.

Find the sum of the following series : 1.3+3.5+5.7+ .... to n terms .

Find the sum of the following series : 1^3+3^3+5^3 + .... to n terms .

Find the sum of the following series : 3.1^2+5.2^2+7.3^2 + .... to n terms .

Find the least value of n for which the sum 1 + 3 + 3^2 +...... to n terms is greater than 7000.

Find the sum of indicated number of terms of the following A.P.’s : 5, 2, -1, - 4, -7, ......., n terms.

Find the sum to indicated number of terms of the geometric progressions given below:- x^3, x^5, x^7, ... n terms( if x ne +-1 ).

If alpha is the nth root of unity then prove that 1+2 alpha+ 3 alpha^2+…. upto n terms

Find the sum of the series upto n terms 0.b+0.b b+0.b b b +0.b b b b+"......",AA " b" in N " and "1 le b le 9.

If the sum of n terms of two A.P.s are in the ratio 7n + 1 : 4n + 27. Find the ratio of their 11^(th) terms.