And so we can substitute our expression for the first derivative back here to have this expression in terms of x and y. And so this is all going to be equal to, let me write it over here, the second derivative of y with respect to x is going to be equal to two minus, well, the derivative of y with respect to x, we already know, is two x minus y. Two x minus y. And so this is going to be equal to two minus two x plus y. Plus y. And then they say, determine the concavity of all solutions for the given differential equation in quadrant two. Remember, if you're thinking about our coordinate axes, if you think about our coordinate axes, so if that's our y-axis, that is our x-axis, this is quadrant one, this is quadrant two, this is quadrant three, and this is quadrant four.