△=(-2m)²-4×(-2m-4)
=4m²+8m+16
=4(m²+2m+1)+12
=4(m+1)²+12
(m+1)²≥0
所以4(m+1)²+12恒大于0
所以不论m为何值时,方程总有两个不相等的实数根