1、（1）2b/a；（2）(x+y)xy；（3）x(x+y)/(x+y)²=x/(x+y)；(4)(x+y)(x-y)/(x-y)²=(x+y)/(x-y).
2、（1）2c/bd=(2c)·(4b)/(4b²d)=8bc/(4b²d)；
3ac/(4b²)=3ac·d/(4b²d)=3acd/(4b²d)
（2）2xy/(x+y)²=2xy(x-y)/[(x+y)²(x-y)]
x/(x²-y²)=x/[(x-y)(x+y)]=x(x+y)/[(x-y)(x+y)²]
1、（1）2b/a；（2）(x+y)xy；（3）x(x+y)/(x+y)²=x/(x+y)；(4)(x+y)(x-y)/(x-y)²=(x+y)/(x-y).
2、（1）2c/bd=(2c)·(4b)/(4b²d)=8bc/(4b²d)；
3ac/(4b²)=3ac·d/(4b²d)=3acd/(4b²d)
（2）2xy/(x+y)²=2xy(x-y)/[(x+y)²(x-y)]
x/(x²-y²)=x/[(x-y)(x+y)]=x(x+y)/[(x-y)(x+y)²]