For an equation like ax^{2} + bx + c = 0 we have
b^{2} - 4ac or DELTA is smaller than zero thus having no
real root if:

1- a,c > |b|

2- a=b=c

3- a=b and c>b for positive b. You can swap a and c

I've proved it but since it's trivial, I didn't put it here.