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

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).

 

If:

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.

AG

Related Maths GCSE answers

All answers ▸

Write 144 as a product of its prime factors


Show clearly that (3√3)^2 = 27


How do you solve a quadratic equation e.g. x^2 - 5x - 14 = 0?


A roll of card has an area of 43 m^2. A postcard has an area of 125 cm^2. How many post cards can be cut from the roll, assuming there is no wastage? (calculator question)