How do I find the discriminant? - Answers

Given the quadratic equation ax^2 + bx + c =0, where a, b, and c are real numbers: (The discriminant is equal to b^2 - 4ac) If b^2 - 4ac < 0, there are two conjugate imaginary roots. If b^2 - 4ac = 0, there is one real root (called double root) If b^2 - 4ac > 0, there are two different real roots. In the special case when the equation has integral coefficients (means that all coefficients are integers), and b^2 - 4ac is the square of an integer, the equation has rational roots. That is , if b^2 - 4ac is the square of an integer, then ax^2 + bx + c has factors with integral coefficients. * * * * * Strictly speaking, the last part of the last sentence is not true. For example, consider the equation 4x2 + 8x + 3 = 0 the discriminant is 16, which is a perfect square and the equation can be written as (2x+1)*(2x+3) = 0 To that extent the above is correct. However, the equation can also be written, in factorised form, as (x+1/2)*(x+3/2) = 0 Not all integral coefficients.