Find the sum of 8 terms and n terms of the sequences 9,-3,1,……….

Find the sum to n terms of the sequence : 1,-1,1,-1,........ ,(-1)^(n+1) , ..........

Find the sum of n terms of the following sequences: 8+88+888+……………..up to n terms.

Find the sum of the products of the corresponding terms of the sequences 2, 4, 8, 16, 32 and 128, 32, 8,2, 1/2 .

If the first four terms of an arithmetic sequence are a,2a,b and (a-6-b) for some numbers a and b, find the sum of the first 100 terms of the sequence.

Find the sum to n terms of the sequence {a_n} , where a_n=5-6n, n in N .

Find the sum of the first a terms of the series whose nth term is: n(n + 3) .

Find the sum of the first 22 terms of the AP: 8, 3, -2, ………

Find the sum of the first a terms of the series whose nth term is: 3n^2+5 .