need help with a 3 part problem. I got the radius correct but would still like a simple breakdown of the proccess

Question

Part a: Assume that the height of your cylinder is 8 inches. Consider A as a function of r, so we can write that as A(r)=2πr^2+16πr. What is the domain of A(r)? In other words, for which values of r is A(r) defined?

 

Part b: Continue to assume that the height of your cylinder is 8 inches. Write the radius r as a function of A. This is the inverse function to A(r), i.e to turn A as a function of r into. r as a function of A.

r(A)= ?

Part c: If the surface area is 150150 square inches, then what is the radius r? In other words, evaluate r(150). Round your answer to 2 decimal places.

I was able to get a correct answer of 2.31 for the radius if the surface area is 150 square inches.

Answer 1