The concentration C in part per million, of a medication in the body t hours after ingestion is give by the function

C(t)= 10t^2e^-t

1. Find the rate of change of the concentration

I know this is the derivative, but the derivative the book give me is not like the one I got. I have

C'(t)=20te^-t - 10t^2e^-t

2. Find the maximum value of the concentration and where it occurs.