已知x-3y=2,x+y=5,则x2-2xy-3y2=______.
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已知x-3y=2,x+y=5,则x2-2xy-3y2=______.
![已知x-3y=2,x+y=5,则x2-2xy-3y2=______.](/uploads/image/z/19678876-52-6.jpg?t=%E5%B7%B2%E7%9F%A5x-3y%3D2%EF%BC%8Cx%2By%3D5%EF%BC%8C%E5%88%99x2-2xy-3y2%3D______%EF%BC%8E)
∵x-3y=2,x+y=5,
∴x2-2xy-3y2=(x-3y)(x+y)=2×5=10.
故答案为:10.
∴x2-2xy-3y2=(x-3y)(x+y)=2×5=10.
故答案为:10.
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