# Given #A=2(pi)r^2 + 2(pi)rh#, how do you solve for r?

##### 2 Answers

This cannot be done.

#### Explanation:

My thinking here says that it cannot be done, because there are two different powers of r involved. If you try to factor out the r as a common factor, there will still be an r in the first term.

Use the quadratic formula to get

#### Explanation:

Although at first it seems like we can't solve, for

Note that if subtract

If we take out the

We know that

Making the substitutions

Certainly not the cleanest expression, but it will do.