0
x + y + z = 0
4
Lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 will be mutually perpendicular if.
a1 b2 - b1 a2 = 0
a1 a2 + b1 b2 = 0
a12 b2 + b12 a2 = 0
a1 b1 + a2 b2 = 0
x - y = -5
x - y - 2 = 0
