For what values of $\lambda$ does the following set of equations have nontrivial solutions for $x, y$. z? For each value of $\lambda$ find the corresponding solutions for $x, y, z$. (Comment: This is an example of what is called an eigenvalue or characteristic value problem in mathematica] physics; the values of $\lambda$ are the eigenvalues. See Chapters 10 and $12 .$ )
$$
\left\{\begin{array}{r}
-(1+\lambda) x+y+3 z=0 \\
x+(2-\lambda) y=0 \\
3 x+(2-\lambda) z=0
\end{array}\right.
$$