Does $|d(x_n.a)-d(a,x)|\leq d(x_n,x)$?
88605
Proof of the Reverse Triangle Inequality
55016
Prove that if ($d(x,y)=0$ iff $x=y$) and if $d(x,z)\leq d(x,y)+d(z,y)$ then $d$ is a metric
147661
Show that {$x_n$} is a convergent sequence if $d(x_{n+2}, x_{n+1})≤ rd(x_{n+1}, x_n)$
31846
Does $\neg(x > y)$ imply that $y \geq x$?
59724
Proving that $x_n\to L$ implies $|x_n|\to |L|$, and what about the converse?
137614
$\left|\frac{x}{|x|}-\frac{y}{|y|}\right|\leq |x-y|$, for $|x|, |y|\geq 1$?
63036
Proving that $\dim(\mathrm{span}({I_n,A,A^2,...})) \leq n$
39073
Proving that: $\forall n \in \mathbb{N} :|f^{(n)}(x)|\leq \frac{1}{n+1}$
79847
proving of inequality $(n!)^2 \leq n^n\cdot n!\leq (2n!)$, where $n\in \mathbb{N}$
29198
How to prove the following inequality $|\prod_{i=1}^{i=n}a_i-\prod_{i=1}^{i=n}b_i| < n\delta$?
82097
If $A \succeq B$, is it true that $B^{-1} \succeq A^{-1}$?
144372
How to Prove that if $A$ is bounded, then $A \cdot A$ is bounded?
76863
How to show $ \sup \inf g(x,y) \leq \inf \sup g(x,y)$?
69656
Prove or disprove that $\int_a^b |f(x)|\ \mathrm{d}x\geq \big | \int_a^b f(x)\ \mathrm{d}x\big| $
28822
$|x| - |y| \leq |x-y|?$
148302
In convergence, why not $d \leq \epsilon$?
46106
Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$