Does $\inf(A+B)=\inf(A)+\inf(B)$ really hold?
14162
How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$
105367
Proving $||\vec{a}+\vec{b}|| = ||\vec{a}-\vec{b}|| \iff \vec{a} \perp \vec{b}$
52305
Is there a general relation between $a/b$ and $(a+c)/(b+c)$ where $a,b,c > 0 $?
156573
How is + as an infix operator associated with Plus?
62633
Why doesn't a+++++b work?
98496
Let $a,b \in \mathbb{Q^{+}}$ then $\sqrt{a} + \sqrt{b} \in \mathbb{Q} $ iff $\sqrt{a} \in \mathbb{Q}$ and $\sqrt{b} \in \mathbb{Q}$
155806
(Olympiad Question) $f(2x) + 2f(y) = f(f(x+y))$
53551
$f(A\cap B)=f(A)\cap f(B)$ $\iff$ $f$ is injective.
137534
For what ordinals does $1+\alpha=\alpha$ hold? For what ordinals does $2\alpha=\alpha$ hold?
110661
When does $\sqrt{a b} = \sqrt{a} \sqrt{b}$?
134880
Is there a difference between $y(x)$ and $f(x)$
149068
Prove: Assume $\lim_{n\to\infty}(a_n)=a, \lim_{n\to\infty}(b_n)=b$ then $\lim_{n\to\infty}(a_n+b_n)=a+b$
80199
Do we have always $f(A \cap B) = f(A) \cap f(B)$?
77764
Is "$a + 0i$" in every way equal to just "$a$"?
125348
Does $\det(A + B) = \det(A) + \det(B)$ hold?
32760
Is $\mathbf{Q}(\sqrt{2}, \sqrt{3}) = \mathbf{Q}(\sqrt{2}+\sqrt{3})$?
124097
How does += (plus equal) work?