分式混合运算1-a-b/a-2b除a^2-b^2/a^2-4ab+4b^2+3a/a+b

Question

分式混合运算
1-a-b/a-2b除a^2-b^2/a^2-4ab+4b^2+3a/a+b

Answer 1

原式=1-(a-b)/(a-2b)×(a-2b)^2/(a+b)(a-b)+3a/(a+b)
=1-(a-2b)/(a+b)+3a/(a+b)
=1-(3a-a+2b)/(a+b)
=1-2(a+b)/(a+b)
=1-2
=-1