1.
If the system of linear equations
x+y+z=5x + y + z = 5

x+2y+2z=6x + 2y + 2z = 6

x+3y+λz=μ(λ,μ∈R)x + 3y + \lambda z = \mu \quad (\lambda, \mu \in \mathbb{R})

has infinitely many solutions, then the value of λ+μ\lambda + \mu is: