y=(5x-2)/(4x+3)
=[5/4(4x+3)-23/4]/(4x+3)
=5/4-(23/4)/(4x+3)
由于-(23/4)/(4x+3)不=0
所以,Y不=5/4.
即值域是(-无穷,5/4)U(5/4,+无穷).