prove that $BA=\begin{bmatrix}9 & 0\\ 0 & 9\end{bmatrix}$
8638
If I know $AB$, how can I calculate $BA$?
72092
If $A^2 = I$, $B^2=I$ and $(AB)^2=I$, then $AB = BA$
110381
Prove that if rank(A + B) = rank(A) + rank(B), then col(A) ∩ col(B) = {0}
123275
Prove $[A,B^n] = nB^{n-1}[A,B]$
62474
If $AB=I_n$ and $BA=I_m$ then $n=m$.
9574
How to show that $\det(AB) =\det(A) \det(B)$?
110944
Proving that $AB-BA=cI$ for nontrivial $c \in \mathbb{C}$
37252
How can I show that $\begin{pmatrix} 1 & 1 \\ 0 & 1\end{pmatrix}^n = \begin{pmatrix} 1 & n \\ 0 & 1\end{pmatrix}$?
63119
Let $M=\big( \begin{smallmatrix} A & B \\ C & D \end{smallmatrix} \big)$. Prove $\det(M)=\det(A)\cdot \det(D-C·A^{-1}·B)$.
29568
Prove that the determinant of $ A^{-1} = \frac{1}{det(A)} $- Linear Algebra
6091
Similarity of products $AB$ and $BA$ of square matrices
78224
Suppose $A$ is a general $n \times n$ matrix and $B$ is obtained by interchanging two rows of $A$. Prove that $\det(B) = -\det(A)$
155579
Show that $End_A(A)$ = {$r_a$ | $a ∈ A$}
141173
Are there matrices such that $AB=I$ and $BA \neq I$
98855
Prove $aba^{-1}b^{-1}\in{N}$ for all $a,b$
78736
Check my proof that $(ab)^{-1} = b^{-1} a^{-1}$
108642
$e^A$, where $A= \begin{bmatrix} 0 & \omega \\ -\omega& 0 \end{bmatrix}$