已知x已知x
已知x由x<5/4,可得5-4x>0y=4x-2+1/(4x-5)=4x-5+1/(4x-5)+3=-[5-4x+1/(5-4x)]+35-4x+1/(5-4x)≥2√(5-4x)*1/(5-4x2)=2(当且仅当5-4x=1/(5-4x)取到等号)ymax=-2+3=1