a+b=m-4
ab=m/2
|a|+|b|=根号7
a^+b^+2|ab|=7
(m-4)^+2|(m/2)|=7
(m-4)^+|m|=7
因为判别式大于等于0
(m-4)^2-2m>=0
m^2-10m+16>=0
(m-4)^>=2m
(m-2)(m-8)>=0
若m