Hello there, Today in class, my teacher said the following: The interval over which the implicit solution can be found by considering the quadratic formula . The interval of which can be defined is precisely the interval of which the determinant is real (non-complex). What I'm not sure about is how can we treat the implicit solution as a quadratic, when . Ordinarily, quadratic applies to the form where here and naturally, . But since , my sense is that quadratic can't be used. Thanks for the help.