lz 证了好一会不会啊：（/kk/ll
det(Ix2−Ax−B)=det(Ix−[0IBA])\det(Ix^2-Ax-B)=\det \left(Ix-\begin{bmatrix}0&I\\B&A\end{bmatrix}\right) det(Ix2−Ax−B)=det(Ix−[0BIA])
