Hey guys I can't figure out this question.
let f:A->A be a function fof is injective
Prove wether f is injective or not
Can someone show me what's the proof
THANKS !
This one of a group of three part theorem.
Given any functions $\displaystyle f~\&~g~:$
a) if $\displaystyle g\circ f$ is injective then $\displaystyle f$ is injective,
b) if$\displaystyle g\circ f$ is surjective then $\displaystyle g$ is surjective,
c) if $\displaystyle g\circ f$ is bijective then $\displaystyle f$ is injective and $\displaystyle g$ is surjective.