You can prove 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 simplifying steps are done correctly, it will simply to 0. Derivation of the formula is usually done via the method of completing the square. | You can prove 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 simplifying steps are done correctly, it will simply to 0. Derivation of the formula is usually done via the method of completing the square. |