So this thing in blue, that is u of x. U of x is equal to x squared plus x. And it's going to be useful later on to know what u prime of x is. So that's going to be, just going to use the power rule here. So two x plus one, brought that two out front and decremented the exponent. Derivative with respect to x of x is one. And we could say the log base four of this stuff, well we could call that a function v. We could say v of, well if we said v of x, this would be log base four of x. And then we've shown in other videos that v prime of x is going to be very similar to if this was log base e or natural log, except we're going to scale it.