A quadratic function can be drawn as a parabola on a graph. Find out how to plot the graph in this Bitesize KS3 maths video.

Revise how to recognise and determine the equation of a quadratic function from its graph. BBC Bitesize Scotland revision for SQA National 5 Maths.

But how do you come up with a function to fit data? The basic idea is to create a quadratic function and vary the parameters such that the deviation of the actual data from the function is minimized.