Find the sum to indicated number of terms of the geometric progressions given below:- 0.15, 0.015, 0.0015, ... 20 terms.

Find the sum to indicated number of terms of the geometric progressions given below:- 1,-a, a^2,-a^3 , ... n terms (if a ne -1 ).

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 ).

Find the sum to indicated number of terms of the geometric progressions given below:- sqrt7,sqrt21, 3sqrt7 ,.....n terms.

Find the sums of the indicated number of terms of the following geometric progressions : 2,-1/2,1/8 , ........., n terms, 12 terms.

Find the sums of the indicated number of terms of the following geometric progressions : 1,1/3,1/9 .........., n terms, 5 terms.

Find the sum of indicated number of terms of the following arithmetic progression : 16, 11, 6,..........., n terms, 23 terms.

Find the sums of the indicated number of terms of the following geometric progressions : x^2-y^2,x-y, (x-y)/(x+y) , ...., n terms (x+y ne 1) .

Find the sum of indicated number of terms of the following A.P.’s : - 0.5,-1.0, -1.5 , ............ , 10 terms, 50 terms .

Find the sum of indicated number of terms of the following A.P.’s : 2, 4, 6, ......., 100 terms.