Finding the first derivative. So DDX of X ^3 plus DDX of y ^3 equal DDX of 28. We're going to get 3X squared DX DX plus three y ^2 d Y DX equaling 0. The DX DX is really just one. So take everything that doesn't have a DYDX to one side -3 X squared divided by the three y ^2 and simplify. We get negative X ^2 / y ^2, but we want the 2nd derivative. So now we're going to take the derivative of the derivative. So DDX of DYDX equaling DDX of negative X ^2 / y ^2. So d ^2 y over DX squared equaling the derivative of the top times the bottom minus the derivative of the bottom times the top all over the bottom squared. So -2 XDXD X * y ^2 -, 2 YDYD X * -X ^2. So now we're going to stick in what we found for DYDX. Originally. DYDX is that negative X ^2 / y ^2. So the next line we're going to get -2 XY squared -2 Y instead of DYDX sticking in negative X ^2 / y ^2 * -X ^2. So we get -2 XY squared. 3 negatives multiplied together is going to give us a minus. One of the YS will reduce, so we get 2X to the 4th over Y. If we simplify that to get rid of our complex fraction, we get -2 XY cubed -2 X to the 4th all over Y and then all over Y to the 4th. So that Y and that Y to the 4th is going to make Y to the 5th on the bottom. Now it specifies we want a value at a point. So we're going to now stick in the .13. Every time we see our X, we're going to put one. Every time we see our Y, we're going to put three and we get -56 / 243.