x=1/(根号3-2),y=1/(根号3+2),求代数式(x2+xy+y2)/(x+y)的值
问题描述：
x=1/(根号3-2),y=1/(根号3+2),求代数式(x2+xy+y2)/(x+y)的值
答
x=1/(√3-2)=-2-√3
y=1/(√3+2)=2-√3
x+y=-2√3
xy=-1
(x2+xy+y2)/(x+y)=[(x+y)²-xy]/(x+y)=11/(-2√3)=-11√3/6