And now let's think about differentiability. So in order to be differentiable, I'll just, differentiable, in order to be differentiable, the limit as x approaches three of f of x minus f of three over x minus three needs to exist. So let's see if we can evaluate this. So first of all, we know what f of three is. F of three, we've already evaluated this. This is going to be nine. And let's see if we can evaluate this limit, or let's see what the limit is as we approach from the left-hand side and the right-hand side.