How to find if all vectors are on the same plane?

vectors list: 

A(2,-1,-2) 

B(1,2,1)

C(2,3,0)

D(5,0,-6)

if  (AB×AC)·AD=0 then all vectors are on the same plane.

AB = (-1,3,3) = (1-2,2-(-1),1-(-2))

AC = (0,4,2)

AD = (3,1,-4)

-13304231-4 = 36 - 36 = 0

vectors are on the same plane.