又是一道分式:x/(x^2-2xy+y^2)*(x^3-y^3)/(x^3+x^2y+xy^2)+[1/(x-y)]-2已知:x和y是方程x+2y=4和x-y=-5的解

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又是一道分式:x/(x^2-2xy+y^2)*(x^3-y^3)/(x^3+x^2y+xy^2)+[1/(x-y)]-2已知:x和y是方程x+2y=4和x-y=-5的解

又是一道分式:x/(x^2-2xy+y^2)*(x^3-y^3)/(x^3+x^2y+xy^2)+[1/(x-y)]-2已知:x和y是方程x+2y=4和x-y=-5的解
又是一道分式:x/(x^2-2xy+y^2)*(x^3-y^3)/(x^3+x^2y+xy^2)+[1/(x-y)]-2
已知:x和y是方程x+2y=4和x-y=-5的解

又是一道分式:x/(x^2-2xy+y^2)*(x^3-y^3)/(x^3+x^2y+xy^2)+[1/(x-y)]-2已知:x和y是方程x+2y=4和x-y=-5的解
原式=[x/(x-y)^2]*(x-y)(x^2+xy+y^2)/x(x^2+xy+y^2)+[1/(x-y)]-2
=1/(x-y)+1/(x-y)-2
=2/(x-y)-2
=2/(-5)-2
=-12/5