Question

Prove every group of order 4 is abelian not cyclic

Answer 1

Answer:

All elements in such a group have order 1,2 or 4. If there's an element with order 4, we have a cyclic group – which is abelian. Otherwise, all elements ≠e have order 2, hence there are distinct elements a,b,c such that {e,a,b,c}=G.