Find the characteristic polynomial of M=(1203)M = \begin{pmatrix} 1 & 2 \\ 0 & 3 \end{pmatrix}M=(1023).
λ2−4λ+3\lambda^2 - 4\lambda + 3λ2−4λ+3
λ2−4λ−3\lambda^2 - 4\lambda - 3λ2−4λ−3
λ2+4λ+3\lambda^2 + 4\lambda + 3λ2+4λ+3
λ2−3λ+4\lambda^2 - 3\lambda + 4λ2−3λ+4