=(a/4-b/5)(a/4+b/5-a/4+b/5)
=2b/5(a/4-b/5)你确定对么?怎么算出来的看不懂呀=(a/4-b/5)[(a/4+b/5)-(a/4-b/5)] 先提取公因式(a/4-b/5)=(a/4-b/5)(a/4+b/5-a/4+b/5) 去掉后面的小括号 =2b/5(a/4-b/5)合并同类项超级感谢你,加个好友,以后问题就找你问行么?行，但这个题目先帮我采纳