分式的加减法 1.xx/x-1-x-12.(x-y+4xy/x-y)(x+y-4xy/x+y )3.a-b+2bb/a+b

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分式的加减法 1.xx/x-1-x-12.(x-y+4xy/x-y)(x+y-4xy/x+y )3.a-b+2bb/a+b
分式的加减法
1.xx/x-1-x-1
2.(x-y+4xy/x-y)(x+y-4xy/x+y )
3.a-b+2bb/a+b

分式的加减法 1.xx/x-1-x-12.(x-y+4xy/x-y)(x+y-4xy/x+y )3.a-b+2bb/a+b
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)