Find the equation of the plane through the points (2,1,0), (3,-2,-2) and (3,1,7).
We know that, the equation of a plane passing through three non-collinear points (x1,y1,z1), (x2,y2,z2) and (x3,y3,z3) is ∣∣
∣∣x−x1y−y1z−z1x2−x1y2−y1z2−z1x3−x1y3−y1z3−z1∣∣
∣∣=0⇒ ∣∣
∣∣x−2y−1z−03−2−2−1−2−03−21−17−0∣∣
∣∣=0⇒ ∣∣
∣∣x−2y−1z1−3−2107∣∣
∣∣=0⇒(x−2)(−21+0)−(y−1)(7+2)+z(3)=0⇒−21x+42−9y+9+3z=0⇒−21x+9y+3z=−51∴7x−3y−z=17
So, the required equation of plane is 7x+3y−z=17.