The vector equation of the plane through the line of intersection of the planes x+y+z=1 and 2x+3y+4z=5 which is perpendicular to the plane x-y+z=0 is:
(3)
Let the plane be (x+y+z-1)+λ(2x+3y+4z-5)=0
⇒(2λ+1)x+(3λ+1)y+(4λ+1)z-(5λ+1)=0
⊥ to the plane x-y+z=0
⇒λ=-13
⇒the required plane is x-z+2=0