Algebraic proof that $ ||\vec{a} +\vec{b}|| \le ||\vec{a}|| + ||\vec{b}|| $
91662
Proof for triangle inequality for vectors
67709
Stuck with proof for $\forall A\forall B(\mathcal{P}(A)\cup\mathcal{P}(B)=\mathcal{P}(A\cup B)\rightarrow A\subseteq B \vee B\subseteq A)$
127296
prove that a|b and b|a iff a=+-b
16253
Proof that $|\sin(nx)| \le n|\sin(x)|$
124320
$a,b,c>0 \text{ s.t. }a+b+c=1 \implies \sqrt{ab+c}+\sqrt{bc+a}+\sqrt{ca+b} \ge 1+ \sqrt{ab}+\sqrt{bc}+\sqrt{ca}$
3820
Prove that $||x|-|y||\le |x-y|$
116056
Prove that $|f(x)-f(y)|\le|x-y|$ for all $x$ and $y$.
46780
Proving $((a\bmod n) (b\bmod n))\bmod n = ab\bmod n $
155579
Show that $End_A(A)$ = {$r_a$ | $a ∈ A$}
20346
'Algebraic' way to prove the boolean identity $a + \overline{a}*b = a + b$
35313
Proof of Euclid's Lemma
16109
Prove that $ \int _a^b\:f\left(x\right)\:\:dx\:=\:\int _a^b\:f\left(a+b-x\right)\:\:dx $
81775
Prove $a^\alpha b^{1-\alpha} \le \alpha a + (1 - \alpha)b, \; a,b > 0,\; 0 < \alpha < 1$
138931
Show that $||x+y||\cdot||x-y||\le||x||^2+||y||^2$
8554
Proof: $\mathrm{adj}(\mathrm{adj}(A)) = (\mathrm{det}(A))^{n-2} \cdot A$ for $A \in \mathbb{R}^{n\times n}$
151038
How to prove (A v B), (A → C), (B → D) therefore (C v D)
115606
Proofs involving $ (A\setminus B) \cup (A \cap B)$