Question 30058
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}  this is the formula they are using .... the portion under the root is called the discriminant.

When you calculate this portion you will come out with one of three numbers: A positive, a negative or zero.
if the number is positive, there are two roots (places where the graph crosses the x-axis)
if the number is zero there is only one solution, and the parabala just touches the x-axis
if the number is negative, there are no real solutions and the graph does not cross the x-axis