Revenue for sales of rubber baby-buggy bumpers is given by
R(q)=90q^2-q^3 for 0<q<70 .
a.what is the maximum revenue?
b.at what quantity is revenue increasing the fastest?
I tried finding R'(q)=180q-3q^2
and then from here found out p=-b/2a so that price(p) is set in R'(p) to find the maximum revenue.
I am not quite sure what part b wants.Am I doing part a correct?Any help?