How to solve a quadratic equation?

There are several ways to solve a quadratic equation. 1.Quadratic formula ax² + bx + c = 0, where a can't equal 0 but b and c can.x = (-b± (b² - 4ac)) / 2a2. completing the square(x + b/2)² + c3. factorising by eye
The solution (x) gives the turning point of the curve where the gradient is equal to 0.