已知3x+2y=0,求代数式x^2+xy-y^2/x^2-xy+y^2的值.
问题描述:
已知3x+2y=0,求代数式x^2+xy-y^2/x^2-xy+y^2的值.
答
3x+2y=0 则x= -2/3 y
(x^2+xy-y^2)/(x^2-xy+y^2)
=(4/9 y²-2/3y²-y²)/(4/9 y²+2/3y²+y²)
=(-11/9 y²)/(19/9y²)
= -11/19