Equations of the given planesx+y+z−6=0 .......(i) and 2x+3y+4z+5=0 .......(ii) The equation of the plane passing through the line of intersection of the plane Eqs. (i) and (ii). x+y+z−6+λ(2x+3y+4z+5)=0 ........ (iii) ∵ Plane passing through the point (1,1,1). Hence, 1+1+1−6+λ[2(1)+3(1)+4(1)+5]=0 ⇒−3+14λ=0[ from Eq. (iii) ] ⇒λ=