Sum the following series:
7 + 77 + 777 + ......... to n terms
Let   Â
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Find the least value of n for which the sum 1 + 3 + 32+ ...... to n terms is greater than 7000.
The ratio of the sum of first three terms is to that of first 6 terms of a G.P. is 125 : 152. Find the common ratio.
If S1, S2 and S3 be respectively the sums of n, 2n and 3n terms of a GP., prove that S1 (S3 – S2) = (S2 – S1)2
Let S be the sum, P the product and R the sum of the reciprocals of n terms in a G.P. Prove that