有理数a大于0,b小于0,化简/-a/+/a-b/-/b/-/b-a/

问题描述:

有理数a大于0,b小于0,化简/-a/+/a-b/-/b/-/b-a/

/-a/+/a-b/-/b/-/b-a/ =a+a-b-(-b)-[-(a+b)]
=a+a-b+b+a+b
=3a+b