Matrix/x^2+x -x -x^3+2x^2+5x-1 x^2-x/x invertible/Exercise

Determine for which ${}x\in \mathbb {C}$ the matrix

{\begin{pmatrix}x^{2}+x&-x\\-x^{3}+2x^{2}+5x-1&x^{2}-x\end{pmatrix}}

is invertible.