Further functions

23

Contents:

A Cubic functions [3.2, 3.3]

B Inverse functions [3.9]

C Using technology [2.11, 3.6]

D Tangents to curves [3.5]

Opening problem

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Phone calls from Jamie’s mobile phone cost$1: 10 per minute,

plus a 30 cent connection fee. So, a phone call which lastsx

minutes will cost Jamie C(x)=1: 1 x+0: 3 dollars.

Jamie wants to find theinverseof this function, which is the

function which tells him how long he can talk, for a certain

amount of money.

Can you find this function?

Acubic functionhas the form f(x)=ax^3 +bx^2 +cx+d where a 6 =0anda,b,candd

are constants.

A CUBIC FUNCTIONS [3.2, 3.3]

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Y:\HAESE\IGCSE01\IG01_23\469IGCSE01_23.CDR Monday, 27 October 2008 2:17:50 PM PETER