A G.P. has first term 729 and 7th term 64. Find the sum of its first 7 terms.

The sum of first 5 terms and first 15 terms of an A.P. are equal. Find the sum of its first 20 terms.

If in A.P., 3rd term is 18 and 7 term is 30, then find sum of its first 17 terms

The sum of first 8 terms of an A.P. is 64 and that of first 15 terms is 225. Find the sum of its first 17 terms.

Find an infinite G.P. whose first term is 1 and each term is the sum of all the terms which follow it.

The sum of first 7 terms of an A.P. is 49 and that of first 17 terms of it is 289. Find the sum of first n terms.

If S is the sum to infinite terms of a G.P whose first term is 'a', then the sum of the first n terms is

The 14th term of an A.P. is twice its 8th term. If its 6th term is -8, then find the sum of its first 20 terms.

The sum of first 8 terms and first 24 terms of an A.P. are equal. Find the sum of its 32 terms.

The sum of the first 7 terms of an AP is 63 and the sum of its next 7 terms is 161. Find the 28th term of this AP.

The fifth term of a G.P. is 81 whereas its second term is 24. Find the series and sum of its first eight terms.