2x²+4x+4+1/(x²+2x+2)=3
2(x²+2x+2)+1/(x²+2x+2)=3
令x²+2x+2=a
则
2a+1/a=3
2a²-3a+1=0
(2a-1)(a-1)=0
a=1/2或a=1
a=1/2的时候
x²+2x+2=1/2
2x²+4x+3=0
判别式