How do I know how many roots a quadratic equation has?

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Let ax2 + bx + c = 0 be the equation in question where a,b,c are real numbers with a not equal to 0 (otherwise we would not have a quadratic).



b2 - 4ac > 0 then there are two (real) roots

b2 - 4ac = 0 then there is exactly one (real) root

b2 - 4ac < 0 then there are no (real) roots.

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