proof that if $AB=BA$ matrix $A$ must be $\lambda E$
4280
A linear operator commuting with all such operators is a scalar multiple of the identity.
59397
Eigenvalues of $AB$ and $BA$ where $A$ and $B$ are square matrices
120867
How prove this two symmetric matrices $AB=0$
117533
$|A-\lambda I|$ and $|\lambda I-A|$
17032
If $ab=ba$, Prove $a^2$ commutes with $b^2$
23946
Prove the definitions of $e$ to be equivalent
28584
Eigenvalues and eigenspaces of AB
148108
Let $L=\operatorname{lcm}(o(a), o(b))$ and prove that $(ab)^L =e$.
35874
Show that when $BA = I$, the solution of $Ax=b$ is unique
147490
If matrix $AB=A$, does it mean B must be an identity matrix?
141173
Are there matrices such that $AB=I$ and $BA \neq I$
72507
Does $ab=1$ imply $ba=1$ in a ring?
100968
Why is $|e^{i \lambda z}| |e^{- \lambda y}|= |e^{- \lambda y}|$ here?
130498
Linear algebra proof regarding matrices
55062
$2\times 2$ matrix $C=AB-BA$
31606
Do matrices $ AB $ and $ BA $ have the same minimal and characteristic polynomials?
133482
$AB-BA$ is a nilpotent matrix if it commutes with $A$