(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

That's what I'm supposed to prove.

2. Relevant equations

A functionfis an injection if

f(x_{1})=f(x_{2}) ---> x_{1}=x_{2}

3. The attempt at a solution

I'm just having trouble constructing a formal proof. I mean, it's obvious that f(g(x_{1}))=f(g(x_{2})) then either g(x_{1})=g(x_{2}) or g(x_{1})≠g(x_{2}), and since g(x_{1})≠g(x_{2}) implies x_{1}≠x_{2}, ......

I don't know. I'm getting all tongue-tied. Help me out here.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Composite of two injections is an injection

**Physics Forums | Science Articles, Homework Help, Discussion**