Answer
$2500r^2+5000r+2500$
Notice that the powers of $r$ are in descending order.
Work Step by Step
Use the special product: square of a binomial (see page 28):
$2500(1+r)^2=2500[1^2+2(1)(r)+r^2]=2500(1+2r+r^2)=2500(1)+2500(2r)+2500(r^2)=2500r^2+5000r+2500$
