a) S = [2, 4, 1] + r·[-2, 2, 1] = [x, 0, z] → r = -2 → S = [6, 0, -1]
b) S = [2, 2, 2] + r·[1, 3, 0] = [x, 0, z] → r = -2/3 → S = [4/3, 0, 2]
c) S = [7, 0, 7] + r·[1, 1, 1] = [x, 0, z] → r = 0 → S = [7, 0, 7]
d) S = [7, 1, 9] + r·[1, 0, 0] = [x, 0, z] → Keine Lösung