Equation of plane containing the given planes is (x+2y+3z+1)+λ(x−y−z−6)=0 (1+λ)x+(2−λ)y+(3−λ)z+(1−6λ)=0 This plane is perpendicular to the plane −2x+y+z+8=0 So, −2(1+λ)+(2−λ)+(3−λ)=0 −2−2λ+2−λ+3−λ=0 λ=
3
4
So, equation of required plane is 7x+5y+9z=14 Now, (0,1,1) satisfies the above plane.