meemee686
幼苗
共回答了11个问题采纳率:90.9% 举报
1.x^2/(x-1)-x-1=(x^2-x^2+1)/(x-1)=1/(x-1)
2.(x-y+4xy/x-y)(x+y-4xy/x+y )
=[(x^2-2xy+y^2+4xy)/(x-y)][x^2+2xy+y^2-4xy)/(x+y)]
=[(x+y)^2/(x-y)][(x-y)^2/(x+y)]
=(x+y)/(x-y)
3. a-b+2bb/(a+b)
=(a^2-b^2+2b^2)/(a+b)
=(a^2+b^2)/(a+b)
1年前
4