Find the points at which the graph of the equation has a ver

Find the points at which the graph of the equation has a vertical or horizontal tangent line. (Order your answers from smallest to largest x, then from smallest to largest y.)
16x2 + 9y2

32x + 18yy\' - 96 + 36y\' = 0 y\' = 96-32x/(36+18y) Horizontal tangents- y\'=0 x=3,y=anything. vertical tangents- 1/y\'=0 x=anything, y = -2