If v of x is equal to seven to the x power, v prime of x would be equal to, and we proved this in other videos where we take derivatives, exponentials of bases other than e, this is going to be the natural log of seven, times seven to the x power. So if we are taking v prime of u of x, then notice, instead of an x everywhere, we're going to have a u of x everywhere. So this right over here, this is going to be natural log of seven times seven to the, instead of saying seven to the x power, remember, we're taking v prime of u of x. So it's going to be seven to the x squared minus x power. X squared, x squared minus x power. And then we want to multiply that times the derivative of u with respect to x. So u prime of x, well that's going to be two x to the first, which is just two x, minus one.