We know that the equation of a plane parallel to X -axis is by+cz+d=0 since, it passes through the points (2,3,1) and (4,-5,3) ∴3b+c+d=0 and −5b+3c+d=0 ⇒
b
1−3
=
c
−8
=
d
14
⇒
b
−2
=
c
−8
=
d
14
∴ Equation of plane is −2y−8z+14=0 i.e. y+4z=7 .