# How to use the discriminant to find out how many real number roots an equation has for x^2 - 5x + 7 = 0?

Apr 26, 2018

No real roots

#### Explanation:

$d = {b}^{2} - 4 a c$

If d>0;"two real roots"
If d=0;"one distinct real roots"
If d<0;"no real roots"

$d = {\left(- 5\right)}^{2} - 4 \left(7\right) = 25 - 28 = - 3$

-3<0; "no real roots"