2x-3=y XY=2009,求XY

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2x-3=y XY=2009,求XY
X=?Y=？看错了，XY=209

y=2x-3
则xy=2x^2-3x=2009
x^2-3x/2=2009/2
x^2-3x/2+9/16=2009/2+9/16
(x-3/4)^2=16081/16
x-3/4=±√16081/4
x=(3±√16081)/4
y=2x-3
所以
x=(3-√16081)/4,y=(-3-√16081)/2
x=(3+√16081)/4,y=(-3+√16081)/2
再问：看错了

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