How to prove that if $(ab,n)=1$ then, $(r,n)=1$?
190
Why $\gcd(qb+r,b)=\gcd(b,r)$?
92583
Prove that $N(\gamma) = 1$ if, and only if, $\gamma$ is a unit in the ring $\mathbb{Z}[\sqrt{n}]$
64782
How to prove if $n$ is prime and $n | a^2$ then $n | a$?
80916
How to prove that if $A\subseteq A\times A$, then $A=\varnothing$?
146533
Having problems proving $ \sum_{r=0}^{n}(r+1) \binom{n}{r} = (n+2)2^{n-1} $
36639
Prove by induction that $\sum_{r=0}^{n}\begin{pmatrix}n \\ r \end{pmatrix}=2^k$
20736
Prove the relation $R$ in $N \times N$ defined by $(a,b) \simeq (c,d)$ iff $ad=bc$ is an equivalence relation.
57125
Prove the distributive law $a(b+c)=ab+ac$ for real numbers?
89175
Proof of $(a+b)^{n+1}$
81794
Prove that $(ab,cd)=(a,c)(b,d)\left(\frac{a}{(a,c)},\frac{d}{(b,d)}\right)\left(\frac{c}{(a,c)},\frac{b}{(b,d)}\right)$
83475
Prove Or Disprove: tr(AB)=tr(A)*tr(B)
73938
Prove that $\sum_{r=1}^nr(r+1)=\frac{n(n+1)(n+2)}{3}$ using induction
31783
Is this proof of $ab = 0$ correct?
83938
If$(ab)^n=a^nb^n$ & $(|G|, n(n-1))=1$ then $G$ is abelian
2289
Prove that if $\gcd( a, b ) = 1$ then $\gcd( ac, b ) = \gcd( c, b ) $
78736
Check my proof that $(ab)^{-1} = b^{-1} a^{-1}$
23066
If $\gcd(a, b) = 1$, then $\gcd(ab, c) = \gcd(a, c) \cdot\gcd(b, c)$