And we're going to find the difference between this expression, the antiderivative evaluated at four and at two. Now what is the antiderivative of six x to the negative three? Well here once again we can just use, we could use as a power rule for taking the antiderivative, or it's the reverse of the derivative power rule. We know that if we're taking the integral of x to the n dx, the antiderivative of that is going to be x to the n plus one over n plus one. And if we were just taking an indefinite integral, there would be some plus c. The reason why we don't put the plus c's here is when you evaluated both bounds of integration, the c would cancel out regardless of what it is. So we don't really think about the c much when we're taking indefinite integrals. But let's apply that to six x to the negative third power.