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

((n choose 2) choose 2) = 3(n choose 4) + 3(n choose 3)

Need a combinatorial proof...

2. Relevant equations

for example, (n choose k) means from a total of n people we choose a committe of size k.

(though this may not be relevant equation)

3. The attempt at a solution

I'm thinking for the left hand side that out of a total of n people we find the all the possible committees of size 2. Then of all these committees we pick two of the duos picked? No idea how to do the right hand side - or make the left side equal

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# Homework Help: Combinatorial proof?

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