Find the characteristic polynomial of the matrix A=(3102)A = \begin{pmatrix} 3 & 1 \\ 0 & 2 \end{pmatrix}A=(3012).
λ2−5λ+6\lambda^2 - 5\lambda + 6λ2−5λ+6
λ2−4λ+3\lambda^2 - 4\lambda + 3λ2−4λ+3
λ2−5λ+3\lambda^2 - 5\lambda + 3λ2−5λ+3
λ2−6λ+9\lambda^2 - 6\lambda + 9λ2−6λ+9