Proof by contradiction attempt pertaining to divisibility
40626
Suppose that $ a,b \in \mathbb{Z}$ If 4 divides $ a^2 + b^2$, then $a$ and $b$ are not odd.
107725
Prove that if $n$ is not divisible by $5$, then $n^4 \equiv 1 \pmod{5}$
76635
Proof through combinatorial argument
95588
Prove by Contradiction: if $4\mid a^2 + b^2$, then $a$ and $b$ are not both odd
10191
Binomial theorem: divisibility by $n^2$
81267
A simple doubt in number theory problem.
75387
A proof that $1=2$. May I know why it’s false?
5183
Divisibility of determinant.
135807
I'm having trouble with a proof by induction
91178
chain of divisibility relation
53123
Trying to derive a contradiction with this simple inequality,
22584
Can we prove that a statement cannot be proved?
125512
Doubt regarding divisibility of the expression: $1^{101}+2^{101} \cdot \cdot \cdot +2016^{101}$
31555
Divisor of $m$ and $n$ divides $m - qn$ (in proof of Euclidean algorithm)
20658
Difficulty in finding a counterexample
126633
Is a contradiction enough to prove a set equality to $\varnothing$?
48908
Choose 100 numbers from 1~200 (one less than 16) - prove one is divisible by another!