Negative 2 3rds minus one power. So what is this going to be? So we get g prime of x is equal to, is equal to seven cosine of x, and let's see, we have a negative three times a negative sine of x, so that's a positive three sine of x. And then, we're subtracting, but then this is going to be a negative, so that's going to be a positive. So we could say plus two pi squared over three, two pi squared over three, that's that part there, times x to the, so negative 2 3rds minus one, we could say negative one and 2 3rds, or we could say negative 5 3rds power. Negative 5 3rds power. And there you have it, we were able to tackle this thing that looked a little bit hairy, but all we had to use was the power rule and what we knew to be the derivatives of sine and cosine.