Final answer:
The expression in brackets in the formula for the future value of an annuity is used to calculate the future value of the annuity, not the interest rate, number of compounding periods, or present value.
Step-by-step explanation:
In the equation for the future value of an annuity, the expression within the brackets represents the accumulation of each annuity payment compounded at the given interest rate over the number of periods until the end of the annuity term. This expression is not simply the interest rate, the number of compounding periods, nor the present value of the annuity. Instead, it is used to calculate the future value of the annuity, which is the amount that will be accumulated in the future after all payments are made and interest is applied.