The sum to the first 25 terms of the series 1 + 2 + 3......... is

How many terms of the G.P 3, 3², 3³,...... are needed to give the sum 120?

How many terms of the G.P 3, 3/2, 3/4......... are needed to give the sum 3069/512?

The number of terms of  A.P 3, 7, 11, 15. . .  where the sum is 406 is

10^th term of an A.P is 52, 16^th term is 82 then t_n  will be        

Which terms of the G.P 2, 2√2, 4,........ is 128?

If the sum of n terms of an A.P is (Pn + qn²) where p and q are constants. Then the common difference is

If the sum of 3 numbers in A.P is 24 and their product is 440, then the numbers are

If -2/7, x, -7/2 are in G.P, then x =

Given a_n = (n+1)²/n then a₇ is