1-a-b/a+2b÷a²-b²/a²+4ab+4b²

来源：学生作业学帮网编辑：学帮网时间：2024/06/01 19:27:39

=1-(a-b)/(a+2b)×(a+2b)/(a+b)(a-b)
=1-(a+2b)/(a+b)
=[(a+b)-(a+2b)]/(a+b)
=-b/(a+b)