using this formula, I'm trying to figure out the problem below

formula: f(a+h)-f(a)/h

Original prob is P(r)=500(1+r)^2

r=0.07 & h=0.01

I want to do this:

500(1+(r+h))^2/h

So 500(1+(0.07+0.01))^2 / 0.01

but it doesn't come ouut w/the answer in the book. Where am I going wrong? Can you help me step by step? Math is so hard for me to grasp. then they mix up the letters!

Thanks a bunch!