6/(x²+x)=x²+x+1
令x²+x=y
6/y=y+1
y²+y-6=0
(y+3)(y-2)=0
y1= -3 y=2
x²+x+3=0
Δ=1-12= -11
无实根
x²+x-2=0
(x+2)(x-1)=0
x1=-2 x2=1