6. Show that the line with parametric equations x = 3 + 8t, y = -5 + t, z = 1 + 3t does not intersect the plane with equation 2x - y - 5z - 2 = 0. 7. Determine the intersection, if any, of the planes with equations x + y - z + 12 =0 and 2x + 4y - 3z + 8 = 0. 8. Solve the following system of equations and give a geometrical interpretation of the result. x- y+z=-2 2x - y - 2z =-9 3x + y- z=-2