Which of these congruences have solutions?
6160
How to prove a number $a$ is quadratic residue modulo $n$?
28594
Number of integer solutions of the following equation
42032
Find all solutions to $x^2\equiv 1\pmod {91},\ 91 = 7\cdot 13$
77533
What solutions does the equation 4x≡2mod10 have? (Hint, it will have more that one.) What about solutions to an equation ax≡dmodn, where d=gcd(a,n)?
123441
Quadratic congruences problem $(x^2-a)(x^2-b)(x^2-ab)$ ≡ 0 (mod p)
7085
Prove that if the equation $x^{2} \equiv a\pmod{pq}$ has any solutions, then it has four solutions.
14809
Existence & uniqueness of solutions of linear congruences $\ cx\equiv b\pmod m$
45882
Solving a congruence without Fermat's little theorem
129381
Modular equation problem
51153
Number of solutions to $x^2\equiv a\pmod m$
144025
Number of Solutions in this Number Puzzle
114379
Show that number of solutions satisfying $x^5=e$ is a multiple of 4?
14773
Finding distinct solutions for the equation
82137
Given a, b How many solutions exists for x, such that: $a \bmod{x}=b $
127945
Number of solutions to the congruence $x^q \equiv 1 \mod p$.
126725
If $p$ is prime and $p$ $\equiv$ $1$ (mod 4), then the congruence $x^2$ $\equiv$ $-1$ (mod $p$) has two incongruent solutions...
41890
How to get all solutions of $x^2 \equiv$ $a$ mod $p$?