Changes

:<math>x = \frac{-b \pm \sqrt {b^2-4ac}}{2a}</math>

:<math>x = \frac{-b \pm \sqrt {b^2-4ac}}{2a}</math>

This method of deriving the formula is done via the method of [[completing the square]].

This method of deriving the formula is done via [[completing the square]].

You can assert that the formula is correct by substituting the formula in place of '''x''' in <math>ax^2+bx+c=0\!</math> and then gradually simplifying the rather complicated formula that results, step by step.  Eventually, if all the steps are done correctly, it will simplify to 0.   

You can assert that the formula is correct by substituting the formula in place of '''x''' in <math>ax^2+bx+c=0\!</math> and then gradually simplifying the rather complicated formula that results, step by step.  Eventually, if all the steps are done correctly, it will simplify to 0.