Tad Dunne <[EMAIL PROTECTED]> writes: > I'm working on an Excel spreadsheet and need a formula or function that > will give, > > for an input A and B, the sum of all the powers of A for integers from > 1 to B. > Example: 1.05 + 1.05 squared + 1.05 cubed ...
S = A + A^2 + A^3 + ... + A^(B-1) + A^B
= A + A*( A + A^2 + A^3 + ... + A^(B-1) + A^B ) - A^(B+1)
= A + A*S - A^(B+1)
S*(1-A) = A - A^(B+1)
1 - A^B
S = A * -------
1 - A
Cheers,
Art Carlson
