Finding the discriminant

When finding the discriminant of a solution the equation is b^2 -4ac . You use this equation to find the number of solutions an equation has.  Lets say you have the equation x^2 +6x +9=0 . First you identify a,b & c . In this equation a=1 , b=6 & c=9 , you plug all the letters into the equation to get 6^2-4(1)(9)=0 which equals 0. When getting this final answer you have to know that if the answer is less than 0 there is no solution, when it is greater than 0 you will get 2 solution and if it equals 0 you will get 1 solution. Since the answer was 0 , the number of solutions is 1.