x-y=5,xy=6,求x的平方y+xy的平方

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x-y=5,xy=6,求x的平方y+xy的平方
x-y=5,xy=6,求x的平方y+xy的平方

x-y=5,xy=6,求x的平方y+xy的平方
∵(x+y)²
=(x-y)²+4xy
=5²+4×6
=25+24
=49
∴x+y=±7
x²y+xy²
=xy(x+y)
=6×(±7)
=±42
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x-y=5, xy=6
﹙x-y﹚²=5²
﹙x+y﹚²-4xy=25
﹙x+y﹚²=25+4×6=49
x+y=±7
x²y+xy²=xy﹙x+y﹚=6×﹙±7﹚=±42.

x-y=5
(x-y)^2=25
(x+y)^2-4xy=25
(x+y)^2=49
x+y=±7
所以原式=x²y+xy²
=xy﹙x+y﹚
=6×﹙±7﹚
=±42.

x - y = 5
xy = 6

(x - y)"
= x" - 2xy + y"
= 25

(x + y)"
= x" + 2xy + y"
= (x - y)" + 4xy
= 25 + 24
= 49
= 7" 或 (-7)"

x"y + xy"
= xy (x + y)
= 6 X 7
= 42
或者
= 6 X (-7)
= - 42