Is it true that $\max\{a+b,\,c+d\} \leq \max\{a,\,c\}+\max\{b,\,d\}$, for any $a,b,c,d \in \mathbb{R}$?
57096
Show that $\max{\{|a|+|b|,|c|+|d|\}} \leq \max{\{|a|,|c|\}}+\max{\{|b|,|d|\}}.$
88687
Proof of the inequality $||a+b|^p - |a|^p| \leq \epsilon |a|^p + C_{\epsilon} |b|^p$
44144
If $f:[a,b]\to \mathbb R$ is continuous then so is $\max_{t\in [a,x]}f(t)$?
79491
Inequality $(a+b)^2 + (a+b+4c)^2\ge \frac{kabc}{a+b+c}$ for $a,b,c \in\mathbb{R}$
83124
Maximize :: $A = B \times C$
62958
Maximize $\mathrm{tr}(Q^TCQ)$ subject to $Q^TQ=I$
5369
Proving the inequality $|a-b| \leq |a-c| + |c-b|$ for real $a,b,c$
41026
How to prove and interpret $\operatorname{rank}(AB) \leq \operatorname{min}(\operatorname{rank}(A), \operatorname{rank}(B))$?
58629
Show that the $\max{ \{ x,y \} }= \frac{x+y+|x-y|}{2}$.
44269
If $f$ is nonnegative and continuous on $[a,b]$, then $\left(\int_a^b f(x)^n \ dx\right)^{1/n}\to\max\limits_{[a,b]} f$
131596
Symmetric Inequality in $\mathbb{R}$
107173
If $a\lt{b}$ and $c\le{d}$, prove that $a+c\lt b+d$
18530
Given 4 integers, $a, b, c, d > 0$, does $\frac{a}{b} < \frac{c}{d}$ imply $\frac{a}{b} < \frac{a+c}{b+d} < \frac{c}{d}$?
143900
how can be prove that $\max(f(n),g(n)) = \Theta(f(n)+g(n))$
5440
Maximum of sum of finite modulus of analytic function.
29679
Prove: $|x-y|\leq |x|+|y|$
116273
Does every $\mathbb{R},\mathbb{C}$ vector space have a norm?