y=(5x+2.5-3.5)/(4x+2)
=[5(x+0.5)-3.5]/4(x+0.5)
=5(x+0.5)/4(x+0.5)-3.5/4(x+0.5)
=5/4-7/(8x+4)
7/(8x+4)≠0
5/4-7/(8x+4)≠5/4
值域(-∞,5/4)∪(5/4,+∞)