△=(-4m)^2-4(m+3)*2m=16m^2-8m^2-24m=8m^2-24m=8m(m-3)＞0
x=[4m±根号△]/[2(m+3)]
负根绝对值大,∴m＜0且根号△＞-4m,即8m^2-24m＞16m^2,m^2+3m＜0,m＜-3
m＜0,∴(m-3)＜0,∴m＜3
∴m＜-3