for the roots to be complex, the discriminant must have a negative value.
having the discriminant as
[tex] \sqrt{b^2-4ac} [/tex] or you can just check
b² - 4ac
where c = m
for the answer to have a negative value, 4ac must be greater than b²
then you'll have:
4(5)c > (-5)²
20c > 25
c > 5/4
c > 1.25
or
m > 5/4 or 1.25
