The Quadratic Formula
The quadratic formula is 
This is used to find the roots of a quadratic, 
The part inside the square root, or 
is called the discriminant
When the discriminant is equal to 
the quadratic only has one root
which is called a double root. If the discriminant is negative, the quadratic has two non
real roots so the roots are complex If the discriminant is positive then the quadratic has two real roots.
