P=(2,1,0)
Q=(1,5,2)
R=(-1,13,6)
Are P, Q, and R collinear? If not, find a vector normal to the plane containing them.
vector PQ = [-1,4,2)
vector RQ = [2,-8,-4)
looks like
RQ = -2[-1,4,2] = -2 PQ
Since one is a scalar multiple of the other , they are collinear.