Answer #20 only handwritten pls

18. Calculate the double points of the following conic section x' + 4 x y + 3 y: - 2xz - 4 y z + 2'=0. Ans. x = 1, y = 0, z=1 19. Calculate the double points of the following conic section x" + 2 x y + y - 8 xz - 8 yz+ 16 2*= 0. Ans. (x + y - 4z) =0 20. Calculate the tangent line in point P(2,0) of the conic section x - 4 x y - y' + 2x - 4 y - 8 =0. Ans. x - 2 y - 2z=0