Quadratic Function - GCSE Maths Definition

A quadratic function is a function of the form

f(x) = ax² + bx + c

where a, b and c are constants and x is the unknown (independent) variable. a ≠ 0 (this would make it a linear function).

The solutions to f(x) = 0 are called the roots (of the function). The graph of y = f(x) is a symmetrical curve called a parabola, the curve will intersect the x-axis at the roots (if there are any) and the y-intercept will be the point (0, c).

In GCSE Mathematics, you may be asked about the various aspects of quadratic functions and how they link together; for example, how the solutions (roots) relate to the graph and how the symmetry of the graph can help solve problems.