Question

How do I do this problem step by step?

A deposit of P dollars is made at the beginning of each month into an
account earning an annual interest rate r, compounded monthly. The
balance of money A after t years in the account is represented by the
following series:

A = P (1 + r/12) + P(1 + r/12)^2 + ... + P(1 + r/12)^12t

Show that the balance is:

A = P[(1 + r/12)^12t - 1](1 + 12/r)

Answer 1

prove by induction?

Answer 2

I think it's a sum of GS...

Answer 3

yep, ur right, it is a geometric series