2x-y=1/3,xy=3,求4x^3y-4x^2y^2+xy^3我说的是XY=3.不是2

2x-y=1/3,xy=3,求4x^3y-4x^2y^2+xy^3我说的是XY=3.不是2
2x-y=1/3,xy=3,求4x^3y-4x^2y^2+xy^3
我说的是XY=3.不是2

2x-y=1/3,xy=3,求4x^3y-4x^2y^2+xy^3我说的是XY=3.不是2
4x^3y-4x^2y^2+xy^3=xy(4x^2-4xy+y^2)=xy(2x-y)^2=3*(1/3^2)=1/3

2X-Y=1/3
XY=2
4X^3y-3x^2y^2+xy^3
= 4X^3y-4x^2y^2+xy^3 + x^2y^2
= xy (4X^2-4xy+y^2) + x^2y^2
= xy(2x-y)^2 + x^2y^2
= 2 * (1/3)^2 + 2^2
= 2/9 +4
= 38/9

已经做在图片上了