Question

已知,xy满足y²=-x²+2x-5/4-y,代数式xy/x+y=

Answer 1

y²=-x²+2x-5/4-y,

——》(y+1/2)^2+(x-1)^2=0,

——》x=1,y=-1/2,

——》xy/(x+y)=1*(-1/2)/(1-1/2)=-1.