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Investigate the effect of changing a and b.
Make sure that you are clear about these aspects of a quadratic graph:
• its basic shape
• its symmetry
• the number of places where the curve crosses the x-axis
• how the values of a and b affect the shape and position of the curve

## Summary/Background

A note about graphic calculators
A graphic calculator is not allowed in your exam. However you can use one for revision. The TI-83, or similar model, can display cubic graphs for you.
 Select the Y= screen:Enter Y1 = (X-A)(X-B)Then select the GRAPH screen. You can then choose different values for the constants A and B. For example, to make A = 1, press 1 ALPHA A.

If your computer is set up with either Omnigraph or Autograph then you can download these files to investigate quadratic curves further.
Investigate quadratic curves further using Autograph.
Investigate quadratic curves further using Omnigraph.

JSXGraph is a cross-browser library for interactive geometry, function plotting, charting, and data visualization in a web browser. It is implemented completely in JavaScript, does not rely on any other library, and uses SVG and VML. JSXGraph is easy to embed and has a small footprint: less than 100 KByte if embedded in a web page. No plug-ins are required! Special care has been taken to optimize the performance.

## Glossary

### cubic

A mathematical expression of the 3rd degree; having a x³ term but no higher one.

### function

A rule that connects one value in one set with one and only one value in another set.

### graph

A diagram showing a relationship between two variables.
The diagram shows a vertical y axis and a horizontal x axis.

### plot

To mark a point on a graph accurately by using its coordinates.