qqp question1: How does watching math videos compare to reading math textbooks in terms of efficiently learning math? question2: How do you determine an expression in terms of [math]A^{-1}[/math] and [math]B^{-1}[/math] for [math]((AB)^T)^{-1}[/math] with [math]A[/math] and [math]B[/math] being matrices of [math]m\times n[/math] size?