Prove that if mn = 1 for integers, then m = n = 1 or m = n = -1

[johnjuwax]

Prove or disprove that if m and n are integers such that mn = 1 then either m= 1 & n = 1 or else m = -1 & n = -1.

 

[Petek]

What have you already tried and where are you stuck?

Petek

 

[VeeEight]

Have you tried to find any counterexamples? Usually that will either disprove the statement or give you a reason why no such counterexamples exist.