For which values of c, cER, will the equation j(x) = c have real roots?
j(x) = 2x^2 - 8x + 5
The Attempt at a Solution
I understand I need to get this into the form of b^2 - 4ac, yet I do not understand why this is important and such. From my understanding, if we make the answer greater than or equal to 0, the roots are real, and if we make it smaller than, the roots are negative. As I don't understand the concept of real roots beyond this, I don't know where exactly to start. This is a question from an exam from a few years ago and I could do everything apart from this for some reason. This was just never explained to me before. Any help would be greatly appreciated.