If the equation F(x,y,z) =0 determines z as a differentiable function of x and y, then, at the points where F, #0, the following equations are true. dz and Use these equations to find the values of dz / dx and dz / dy at the given point. z's - 2xy + 3yz + 2y" - 12=0, (2,1,2) dz dx (2, 1,2 ) (Type an integer or a simplified fraction.) dz = dy (Type an integer or a simplified fraction.) (2,1,2)