We know that image (x,y,z) of a point (x1,y1,z1) in a plane ax+by+cz+d=0 isax−x1=by−y1=cz−z1=a2+b2+c2−2(ax1+by1+cz1+d)Here, point is (3,2,1) and plane is 2x−y+3z=7.∴2x−3=−1y−2=3z−1=22+12+32−2[2(3)−(2)+3(1)−7]⇒2x−3=−1y−2=3z−1=−2(0)⇒x=3,y=2,z=1