若x=1/2,y=1 求x(x²+xy+y²)-y(x²+xy+y²)+3xy(

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若x=1/2,y=1 求x(x²+xy+y²)-y(x²+xy+y²)+3xy(y-x)的值要过程各位帮帮忙啊~

x(x²+xy+y²)-y(x²+xy+y²)+3xy(y-x)
=X^3+X^2Y+XY^2-X^2Y-XY^2-Y^3+3XY^2-3X^2Y
=X^3-3X^2Y+3XY^2-Y^3
=(X-Y)^3
当X=1/2,Y=3时,
原式=(-1/2)^3
=-1/8
再问：能再帮我这道题吗？我会加分的，已知x+y=1/2 ,xy=1 求x^3y+2x^2y^2+xy^3的值
再答： x^3y+2x^2y^2+xy^3 =XY(X^2+2XY+Y^2) =XY(X+Y)^2 =1/2*1^2 =1/2

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