In Exercises use the formula for the nth partial sum of a geometric series

When an employee receives a paycheck at the end of each month, P dollars is invested in a retirement account. These deposits are made each month for t years and the account earns interest at the annual percentage rate r. When the interest is compounded monthly, the amount A in the account at the end of t years is

 When the interest is compounded continuously, the amount A in the account after t years is

Verify the formulas for the sums given above.

n (1 'ar = a(1 r") 1-r i=0