So that's f prime of x. So let's figure out the critical points. The critical points are where this thing is either going to be equal to 0 or it's undefined. 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.