Now, I could look over the entire domain of real numbers and this thing is defined pretty much anywhere. I could put any number here and it's not going to blow up. It's going to give me an answer to what the function is. So it's defined everywhere, so let's just figure out where it's equal to 0. So f prime of x is equal to 0. So let's solve which x is, so let's solve, well I don't have to rewrite that, I just wrote that. Let's solve for whether this is equal to 0, and I'll do it in the same color.