log4(7) × log49(25) ×log125(64)
=(lg7/lg4)×(lg25/lg49)×(lg64/lg125)
=(lg7/g4)×[(2lg5)/(2lg7)]×[(3lg4)/(3lg5)]
=(lg7/lg4)×(lg5/lg7)×(lg4/lg5)
=1