System of Equations Infinitely Many Solutions

If the system of equations
(λ – 1)x + (λ – 4)y + λz = 5
λx + (λ – 1)y + (λ –4)z = 7
(λ + 1)x + (λ + 2)y – (λ + 2)z = 9
has infinitely many solutions, then λ² + λ is equal to