Let's assume that there is a real number a, which makes the two equations hold, so there is a? +ma+ 1=0 and 8a? +a+m=0
So you can get m=-8a? -a, brought into the previous equation, simplified to -8a 3+ 1 = 0.
Get a= 1/2.
Then you get m=-5/2.
That is to say, only when m=-5/2, A∩B= 1/2, and at other times a ∩ b = φ, so as long as m ≦- 5/2 is enough.