Find the value of x such that the points A (3, 2, 1), B (4, x, 5), C (4, 2, – 2) and D (6, 5, – 1) are coplanar.
given the points A(3,2,1) B(4,x,5) , C(4,2,-2) and D(6,5,-1)
and
since the points are coplanar, then