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Determine the equation of a quadratic function from its graphDetermine the equation of a quadratic function from its graph

The equation of a a quadratic function can be determined from a graph showing the turning point and another point on the graph.

Part of MathsAlgebraic skills

Determine the equation of a quadratic function from its graph

Watch this video to learn how to determine the equation of a quadratic function from its graph.

Identify properties of a quadratic function

In this part you do not have to sketch the graph and you may even be given the sketch of the graph to start with.

For a quadratic equation of the form \(y = k{(x - a)^2} + b\), the following diagram shows the main properties:

Diagram of a quadratic equation graph

If k > 0, the vertex is a minimum turning point

If k < 0, the vertex is a maximum turning point

We can identify these properties from a quadratics graph or equation.