a: (2 * x) + (4 * y) + z = 9
u = Vector((2, 4, 1))
f = IntersectPath((x - 4) / 1 + (0 * z) = (y - 1) / -1, (x - 4) / 1 = z / 3)
A = Intersect(f, a)
v = Vector((1, -1, 3))