Find the equation of the tangent plane to the surface z=x2+2xy+3y2z = x^2 + 2xy + 3y^2z=x2+2xy+3y2 at the point (1,1,6)(1, 1, 6)(1,1,6).
z=4x+8y−6z = 4x + 8y - 6z=4x+8y−6
z=4x+8y−2z = 4x + 8y - 2z=4x+8y−2
z=2x+4y+2z = 2x + 4y + 2z=2x+4y+2
z=4x+8y+6z = 4x + 8y + 6z=4x+8y+6