通分方法一览(初二、初三)

摘要

1．约分后通分例1 计算 (x2+2xy+y2)/(x2y+xy2)-(x2-2xy+y2)/(x2y-xy2) 分析分式的分子与分母有公因式,故先约分,然后通分．解原式=(x+y)2/xy(x+y)-(x-y)2/xy(x-y) =(x+y)/(xy)-(x-y)/(xy)=(2y)/(xy)=2/x. 2．整体通分例2 计算a+2-(4/(2-a)．分析把a+2化成(a+2)/1,再进行通分．