All quadratic functions have the same type of curved graphs with a line of symmetry. The graph of the quadratic function \(y = ax^2 + bx + c \) has a minimum turning point when \(a \textgreater 0 \) ...

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.