Use (AB)−1=B−1A−1(AB)^{-1} = B^{-1}A^{-1}(AB)−1=B−1A−1, (A−1)−1=A(A^{-1})^{-1} = A(A−1)−1=A, (AT)−1=(A−1)T(A^T)^{-1} = (A^{-1})^T(AT)−1=(A−1)T.
