Prove function f is surjective.
116732
Proving that a continuous map is surjective
105700
Proving $\,f$ is constant.
152841
I want to show that $f(x)=x.f(1)$ where $f:R\to R$ is additive.
154363
Prove that $\text{aff}(X) = \text{aff}(\text{closure}(X))$
125644
How to check f is surjective
39351
$f(X)$ is uncountable and hence $X$ is uncountable.
121395
Let $X$ and $Y$ be non-empty sets and let $f:X \rightarrow Y$. Prove that $ f^{ −1} :P(Y ) → P(X) $ is injective if, and only if, $f$ is surjective.
121993
Prove that $f$ is one-to-one iff $f \circ h = f \circ k$ implies $h = k$.
10253
Proving that all entire & injective functions take the form $f = ax + b$?
89514
Show that if $g \circ f$ is injective, then so is $f$.
54729
Prove that $f$ has a fixed point .
147021
Proving a function is bounded
84301
Showing that some Function on the Unit Disc is injective
64866
Proving a Composition of Functions is Bijective
75614
Proving that $n|m\implies f_n|f_m$
28798
Proving injection and surjection with functions $F:C^B\to C^A$, $F(f)=f\circ\varphi$, $\varphi: A\to B$
117793
Finding a function $\mathbb{N} \to \mathbb{N}$ that is surjective but not injective.