已知y-x=2,x-3y=1,则x^2-4xy+3y^2的值为

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已知y-x=2,x-3y=1,则x^2-4xy+3y^2的值为
已知y-x=2,x-3y=1,则x^2-4xy+3y^2的值为

已知y-x=2,x-3y=1,则x^2-4xy+3y^2的值为
x^2-4xy+3y^2
=(x-y)(x-3y)
=-2×1
=-2

x^2-4xy+3y^2
=(x-3y)(x-y)
x-3y=1
x-y=-(y-x)=-2
x^2-4xy+3y^2
=(x-3y)(x-y)
=1x(-2)
=-2

x^2-4xy+3y^2=(x-3y)(x-y)=1*(-2)=-2

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