Claim:Injections have left inverses

From CS2800 wiki
If [math]A \href{/cs2800/wiki/index.php/Equality_(sets)}{\neq} \href{/cs2800/wiki/index.php?title=%5Cemptyset&action=edit&redlink=1}{\emptyset} [/math] and [math]f : A \href{/cs2800/wiki/index.php/%E2%86%92}{→} B [/math] is injective, then [math]f [/math] has a left inverse.