y=3-mx
所以x^2+2(3-mx)=6
(m^2+1)x^2-12mx+12=0
有两组相等的实数解则x有两个相同的解
判别式等于0
144m^2-48(m^2+1)=0
96m^2-48=0
m^2=1/2
m=±√2/2
m=√2/2
(3/2)x^2-6√2x+12=0
(3/2)(x^2-4√2x+8)=0
(x-2√2)^2=0
x=2√2,y=3-mx=1
m=-√2/2
(3/2)x^2+6√2x+12=0
(3/2)(x^2+4√2x+8)=0
(x+2√2)^2=0
x=-2√2,y=3-mx=5
所以
m=√2/2,x=2√2,y=1
m=-√2/2,x=-2√2,y=5