Prove or disprove. (If a proof seems difficult to finish, atleast tell what you tried, or how far you got, or what seems tomake the proof difficult.) (a) If a | b, then a 2 | b 2 . (b) If a2 | b 2 , then a | b. (c) If a | b 2 , then a | b. (d) If (a, c) =1 and (b, c) = 1, then (ab, c) = 1. (e) If (a, c) = 1 and (b, c) =1, then (a, b) = 1.
