已知x^2-xy=8,xy-y^2=3,求代数式x^2-y^2和x^-2xy+y^2的值

问题描述:

已知x^2-xy=8,xy-y^2=3,求代数式x^2-y^2和x^-2xy+y^2的值

=8……(1)
=3……(2)
(1)+(2)=x^2-xy+xy-y^2=x^2-y^2=11
(1)-(2)=x^-2xy+y^2=x^2-xy-(xy-y^2)=x^2-xy-xy+y^2=5