$a\cdot x \mod n = 0$, if I know $a$ and $n$, what can I say about $x$?
21241
Proving $\,a\mid bc\!\iff\! \frac{a}{(a,b)}\!\mid c\ $ [general Euclid's Lemma]
114254
Zero divisors in $A[x_1,x_2,\dots,x_r]$
57981
Alternative proof of $a\times0= 0$
57281
Is Bezout's lemma enough to confirm the GCD of a number.
22666
Proving that if $A^n = 0$, then $I - A$ is invertible and $(I - A)^{-1} = I + A + \cdots + A^{n-1}$
97684
Show $\frac{(2n)!}{n!\cdot 2^n}$ is an integer for $n$ greater than or equal to $0$
90496
Proving $\lim \frac{x^n-a^n}{x-a}=n\cdot a^{n-1}$
8160
What is $\gcd(0,a)$, where $a$ is a positive integer?
61825
Congruence class $[a]$ modulo $m$, $\gcd(x, m) = \gcd(a, m)$
41486
If $x^n + a_{n-1}x^{n-1} + ... + a_0 = 0$ has a rational root, then such root is an integer
135385
$0 < a_0 \leq a_1 \leq \cdots \leq a_n$, show $ p_n(z) = a_0 z^n + a_1 z^{n-1} + \cdots + a_{n-1} z + a_n = 0$ has no root in $|z| < 1$
120571
What does it mean $a \;\text{mod}\; 1$?
102042
If $X_n \stackrel{d}{\to} X$ and $c_n \to c$, then $c_n \cdot X_n \stackrel{d}{\to} c \cdot X$
29545
$[(x-a_1)(x-a_2) \cdots (x-a_n)]^2 +1$ is irreducible over $\mathbb Q$
117320
Why is this true: $\|x\|_1 \le \sqrt n \cdot \|x\|_2$?
6160
How to prove a number $a$ is quadratic residue modulo $n$?
23066
If $\gcd(a, b) = 1$, then $\gcd(ab, c) = \gcd(a, c) \cdot\gcd(b, c)$