若x-y=5.xy=6,x^2y+xy^2等于多少

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若x-y=5.xy=6,x^2y+xy^2等于多少若x-y=5.xy=6,x^2y+xy^2等于多少若x-y=5.xy=6,x^2y+xy^2等于多少(X-Y)^2=25X^2+Y^2-2XY=25X

若x-y=5.xy=6,x^2y+xy^2等于多少
若x-y=5.xy=6,x^2y+xy^2等于多少

若x-y=5.xy=6,x^2y+xy^2等于多少
(X-Y)^2=25
X^2+Y^2-2XY=25
X^2+Y^2=25+6*2=37
X^2+Y^2+2XY=(X+Y)^2=37+2*6=49
(X+Y)=+7或-7
X-Y=5
XY=6所以XY同号
所以X+Y=7
解出X=6Y=1
代入即可
答案是42

42
(x+y)^2=(x-y)^2+4xy
题目所求=xy(x+y)

42

X=6,Y=1!当我是来凑热闹的!



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因为:(x+y)²
=x²+2xy+y²
=(x²-2xy+y²)+4xy
=(x-y)²+4xy
=49
那么,x+y=±7
所以,x²y+xy²
=xy(x+y)
=6×(±7)
=±42

解:(x-y)^2=25,(x+y)^2-4xy=25,所以x+y=7,所以x^2y+xy^2=xy(x+y)=6×7=42。

﹙x+y﹚²=﹙x-y﹚²+4xy=5²+4×6=49
∴ x+y=±7
∴ x²y+xy²=xy﹙x+y﹚=6×﹙±7﹚=±42.

,x^2y+xy^2=xy(x+y),
(x+y)^2=(x-y)^2+4xy,
x+y=7,
,x^2y+xy^2=xy(x+y)=6×7=42

(x+y)^2=(x-y)^2+4xy=25+24=49
x+y=7或-7
x^2y+xy^2=xy(x+y)=6*7或6*(-7)=42或-42