先化简,再求值:a2-2ab+b2∕a2-b2+b∕a+b,其中a=-2,b=1

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/16 23:56:50
先化简,再求值:a2-2ab+b2∕a2-b2+b∕a+b,其中a=-2,b=1
x){gu :Ozmlzڰ*H(1I;QT ;H; NyںɎF:I6IE_`gC7h$iCTi?[ٴ ӑdNz*jTS64HԅcA5h]> vt DFQd⧭KmA^5|gN#]CN#mC m n"RD$ըH{'`< "7~.YFHN

先化简,再求值:a2-2ab+b2∕a2-b2+b∕a+b,其中a=-2,b=1
先化简,再求值:a2-2ab+b2∕a2-b2+b∕a+b,其中a=-2,b=1

先化简,再求值:a2-2ab+b2∕a2-b2+b∕a+b,其中a=-2,b=1
(a2+2ab+b2/a2-2ab+b2)3次方 ×(b2-a2/a+b)3次方,
= [ (a+b)²/(a-b)²]³ × [-(a+b)(a-b)/(a+b)]³
= - [ (a+b)²/(a-b)² × (a+b)(a-b)/(a+b) ]³
= - [ (a+b)²/(a-b) ]³
代入a=2,b=-1:
= - [ (2-1)²/(2+1) ]³
= -1/27

=(a-b)²/(a+b)(a-b)+b/(a+b)
=(a-b)/(a+b)+b/(a+b)
=a/(a+b)
当a=-2,b=1时
原式=-2/(-2+1)=2