Question 71936
If the discriminant is greater than zero, then you will have a positive square root. This means you will have 2 roots that are real numbers. 
Ex:  x^2+5x+6 if you put this into the quadratic equation you get
{{{(-5+-sqrt(25-24))/2=(-5+-sqrt(1))/2}}} This further shows that the roots are real numbers of x=-2 and x=-3

{{{graph( 300, 200, -5, 5, -5, 5, x^2+5x+6 )}}}2 real roots

If the discriminant is equal to zero, then you will have only 1 root with multiplicity of 2. 
Ex: x^2+4x+4 place into quadratic formula
{{{(-4+-sqrt(16-16))/2=(-5+-sqrt(0))/2}}}

{{{graph( 300, 200, -5, 5, -5, 5, x^2+4x+4 )}}} 1 real root with multiplicity of 2

If you have a negative discriminant, then no real roots will result since it's not  possible to take the square root of a negative number and get a real result.
Ex: x^2+x+3 if placed into the quadratic formula
{{{(-5+-sqrt(1-12))/2=(-5+-sqrt(-11))/2}}}

{{{graph( 300, 200, -5, 5, -5, 5, x^2+x+3 )}}}No real roots, only complex roots
So a you will have a graph that doesn't cross the x-axis but will have complex roots