y=(5x-1)/(4x-2)
=5/4(x-1/5)/(x-1/4)
=5/4(x-1/4+1/20)/(x-1/4)
=5/4（1+1/20)/(x-1/4)
=5/4+(1/16)/(x-1/4)
定义域x≠1/4
x∈（-∞,1/4）时：
-∞＜x-1/4＜0
-∞＜y＜5/4
x∈（1/4,+∞）时：
-∞＜x-1/4＜0
5/4＜y＜+∞
值域（-∞,5/4）,（5/4,+∞）