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I am having a little bit of a problem solving this proof for my Discreet math course.

If g and f o g are onto(Surjective), is f onto(Surjective)? Need to prove. I belive that f has to be Onto.

so I have g: A -> B

f: B -> C

Well I understand that a function is onto(Surjective) when it maps to all images. So for g all the elements in A map(hit) element in B.

So f o g: A -> C where every element of C must be map to. I belive that since C is the Image of f that this means that f must be onto(Surjective).

Can someone give me advise on how to prove this? Or even just some advise in general on proofs.

TIA

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# Proof Help

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