t = -0.7 (slider from -10 to 10, step 0.1)
P1: (2 * x) + y - z = 6
P2: (3 * x) - y + z = -5
P3: (4 * x) + (t * y) - (2 * z) = -1
h = IntersectPath(P2, P3)
g = IntersectPath(P1, P3)
f = IntersectPath(P1, P2)