In need of help/hints to find A if $(2A)^{-1}$ = $\begin{pmatrix} 3 & 0\\ 2 & 1\\ \end{pmatrix}$
6324
Deriving the inverse of a 2x2 matrix
147014
Matrix algebra: If $A^2=0$, Proof rank(A) $\le \frac{n}{2}$
3330
Square matrices, ABA = A?
145980
For every matrix $A\in M_{2}( \mathbb{C}) $ there's  $X\in M_{2}( \mathbb{C})$ such that $X^2=A$?
7376
Find $\det(A^{2}+A^{T})$ when eigenvalues are $1,2,3$
78736
Check my proof that $(ab)^{-1} = b^{-1} a^{-1}$
107765
Prove that there exists two roots in $[-1,1]$
19285
simplifying $ (h^2_2-h^2_3)\over ({1\over h_3})-({1\over h_2})$
132879
Matlab questions about $a_{n+1} = 4a_{n} + n +1$
99366
Minimum of an expression involving radicals: $\sqrt{\frac{2a}{a+b}} + \sqrt{\frac{2b}{b+c}} + \sqrt{\frac{2c}{c+a}}$
60900
If $A^2=-I$, Prove that $\det{A}=1$
49855
Need a matrix to seventh power which is the identity but the original is not or the negative identity
62382
I suppose $(a,m)=(a-1,m)=1$, show that $1+a+a^2+\ldots+a^{\phi(m)-1}\equiv0\pmod m$
142642
$A=\begin{pmatrix}0&0&1\\ 0&1&0\\ 1&0&0\end{pmatrix}$, $X^2=A$ has no solutions
33560
Show that matrices $A$ and $B$ commute if and only if $\begin{vmatrix} b & a-c \\ e & d-f\end{vmatrix}=0.$
58133
${a^2}{\mid}({b^3} + 1)\;$and$\;{b^2}{\mid}({a^3} + 1)$
15985
simplify $(a_1 + a_2 +a_3+... +a_n)^m$