(cx+d)/(ax+b)是函数ad不等于bc,否则,它为常数c/a.(cx+d)/(ax+b)=[c/a(ax+b)+d-bc/a]/(ax+b)=c/a+(d-bc/a)/(ax+b)后部分,分母不为0,分子d-bc/a不等于0.综上所述：（1）当ad=bc时,它恒等于c/a.(2)ad不等于bc,它不能对...