G is a group and for all elements a,b in G, (ab)^i = (a^i)(b^i) holds for 3 consecutive positive integers. Show that G is abelian. I know how to prove that if (ab)^2 = (a^2)(b^2) then G is abelian. I was thinking that you could reduce the given equality integer by integer till 2 or something like that, but all I have been able to do so far is use the cancellation laws to get some gibberish. HAALP!