If Q220 find P on the surface of zx2y2 so that llPQll is a m

If Q=(2,2,0), find P on the surface of z=x^2+y^2 so that llPQll is a minimum

Distance from P to the x-axis = 2x distance from P to the yz-plane Distance to the x-axis of a point P=(x,y,z) = (y^2+z^2)^1/2 Distance to the yz-plane of a point P=(x,y,z) is x So your equation is: (y^2+z^2)^1/2 = 2x y^2 + z^2 = 4x^2 0 = 4x^2 - y^2 - z^2