已知x+y=-5,xy=3,求代数式x^3y-2x^2y^2+xy^3的值是多少
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2013-06-08
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x^3y-2x^2y^2+xy^3
=xy(x^2-2xy+y^2)
=xy[(x+y)^2-4xy]
=3*[(-5)^2-4*3]
=3*[25-12]
=3*13
=39
=xy(x^2-2xy+y^2)
=xy[(x+y)^2-4xy]
=3*[(-5)^2-4*3]
=3*[25-12]
=3*13
=39
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