分解因式:2xy+9-x^2-y^2

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分解因式:2xy+9-x^2-y^2

分解因式:2xy+9-x^2-y^2
分解因式:2xy+9-x^2-y^2

分解因式:2xy+9-x^2-y^2
2xy+9-x^2-y^2
=9-x^2-y^2+2xy
=9-(x^2+y^2-2xy)
=9-(x-y)^2
=[3-(x-y)][3+(x-y)]
=(3-x+y)(3+x-y)

=9-(x^2-2xy+y^2)
=3^2-(x-y)^2
=(3+x-y)(3-x+y)

2xy+9-x^2-y^2
=9-x^2+2xy+y^2
=9-(x-y)^2
=(3+x-y)(3-x+y)

先使用完全平方公式,再使用平方差公式即可。原式=-(x 2;-2xy+y 2;)+1=1 2;-(x-y) 2; =(1-x+y)(1+x-y) 2xy

2xy+9-x^2-y^2=9-(x²-2xy+y²)=3²-(x-y)²=(3+x-y)(3-x+y)