If Ax = 0 for every x in $R^n$, A is a zero matrix
32155
Prove that if for every $x \in \mathbb{R}^N$ $Ax=Bx$ then $A=B$
17421
Linear Algebra: Find a matrix A such that T(x) is Ax for each x
154327
$A^2X = X$ show that $AX = X$, if $A_{ij} > 0$ and $x_{i} > 0$
15730
Determine the minimum of $a^2 + b^2$ if $a,b\in\mathbb{R}$ are such that $x^4 + ax^3 + bx^2 + ax + 1 = 0$ has at least one real solution
58021
Finding matrix $B$ is not zero matrix where $AB= 0$
84341
Can the determinant of a matrix can be made $0$?
43570
Finding two non-zero matrices where $AX = BA$
138025
How to show the solution of $\dot{x} = Ax $ is an invariant subspace?
36314
If $Ax = Bx$ for all $x \in C^{n}$, then $A = B$.
56818
Prove that if $A$ is positive, then $\exists\;\alpha>0$ such that $\langle Ax, x \rangle\geq \alpha|x|^2$ for $x\in\Bbb{R}^n$
110408
Solving for $A$ in $Ax = b$
105852
How to verify whether or not there exists a vector $x$ such that $Ax > 0$?
25039
Zero vector of a vector space
8360
$\sum_i x_i^n = 0$ for all $n$ implies $x_i = 0$
116908
Basis for set of nxn matrices with trace = 0
52208
Show that a matrix $A$ is singular if and only if $0$ is an eigenvalue.
55820
If $A$ is an $n \times n$ matrix and $ A^2 = 0$, then $\text{rank}(A)\le n/2$.