Question

已知2x^2-xy-3y^2=0,且x不等于-y.求x/{y-[x^2/(x-y)]}的值.

Answer 1

2x²-xy-3y²=0

(x+y)(2x-3y)=0

x=-y,2x=3y

x≠-y

所以y=(2/3)x

原式=(x²+2/3*x²)/(2/3*x²-4/9*x²-x²)=-15/7