The quadratic formula can be used to solve quadratic equations that will not factorise. You will need to learn this formula, as well as understanding how to use it. Key fact The quadratic formula ...

Simultaneous equations Simultaneous examples with no common coefficients Forming and solving simultaneous equations Linear and quadratic equations ... equation to get all terms on 1 side ...

The coefficient a in the quadratic equation determines the direction in ... the focus is a fixed point through which all light rays parallel to the axis of symmetry will reflect off the parabola.