Given the matrix A=(2112)A = \begin{pmatrix} 2 & 1 \\ 1 & 2 \end{pmatrix}A=(2112), find the eigenvalues λ\lambdaλ.
λ=1\lambda = 1λ=1
λ=3\lambda = 3λ=3
λ=2\lambda = 2λ=2
λ=0\lambda = 0λ=0