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若〔AX次方2-2XY+Y次方2〕-〔AX次方2+BXY+2Y次方2〕=6X次方2-9XY+CY次方2成立,求A.B.C

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若〔AX次方2-2XY+Y次方2〕-〔AX次方2+BXY+2Y次方2〕=6X次方2-9XY+CY次方2成立,求A.B.C的值
若〔AX次方2-2XY+Y次方2〕-〔AX次方2+BXY+2Y次方2〕=6X次方2-9XY+CY次方2成立,求A.B.C
题目应是 :若〔AX次方2-2XY+Y次方2〕-〔-AX次方2+BXY+2Y次方2〕=6X次方2-9XY+CY次方2成立,求A.B.C的值
(ax^2-2xy+y^2)-(-ax^2+bxy+2y^2)
=2ax^2-(b+2)xy-y^2
=6x^2-9xy+cy^2 ;比较系数得到
2a=6; b+2=9; c= -1;
所以 a=3,b=7,c=-1.