Quadratic equations

and functions

21

Contents:

A Quadratic equations [2.10]

B The Null Factor law [2.10]

C The quadratic formula [2.10]

D Quadratic functions [3.2]

E Graphs of quadratic functions [3.2]

F Axes intercepts [3.2]

G Line of symmetry and vertex [3.2]

H Finding a quadratic function [3.3, 3.4]

I Using technology [2.10]

J Problem solving [2.10, 3.2]

Opening problem

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A cannonball fired vertically upwards from ground level has height

given by the relationship H=36t¡ 3 t^2 metres, wheretis the

time in seconds after firing.

Things to think about:

1 If we sketch a graph of the heightHagainst the timetafter

firing, what shape will result?

2 How long would it take for the cannonball to reach its

maximum height?

3 What would be the maximum height reached?

4 How long would the person who fired the cannonball have to clear the area?

This chapter is devoted toquadratics, which are expressions of the form ax^2 +bx+c wherexis a variable

anda,bandcare constants.

We will considerquadratic equationsand alsoquadratic functionswhich take the shape of aparabola.

IGCSE01

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Y:\HAESE\IGCSE01\IG01_21\421IGCSE01_21.CDR Monday, 27 October 2008 2:08:46 PM PETER