AAKASH AITS( 3D )

For the abv eq^ns ..the cross product of their normals of the planes..give the direction ratios of the line passing through them..
for it to be a single line..

drs of the line passing through 3x - y - 2z = 0 and x - y + 2z = 0 is (1,4,1)

drs of the line passing through x - y + 2z = 0 and x + y -kz = 0 is (k-2, k+2, 2)
comparing the drs of the two lines K = 6
so ans is D

ans is 6

k= 6 is the ans....