已知x^2-xy=8,xy-y^2=3,分别求下列各式的值：(1)x^2-y^2 (2)x^2-2xy+y^2

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已知x^2-xy=8,xy-y^2=3,分别求下列各式的值：(1)x^2-y^2 (2)x^2-2xy+y^2
已知x^2-xy=8,xy-y^2=3,分别求下列各式的值：(1)x^2-y^2 (2)x^2-2xy+y^2

已知x^2-xy=8,xy-y^2=3,分别求下列各式的值：(1)x^2-y^2 (2)x^2-2xy+y^2
(1)x^2-y^2
=x²-xy+xy-y²
=8+3
=11
(2)x^2-2xy+y^2
=x²-xy-(xy-y²)
=8-3
=5

  1. x^2-y^2=x^2-xy+(xy-y^2)=8+3=11

  2. x^2-2xy+y^2=x^2-xy-(xy-y^2)=8-3=5




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