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CHAPTER 3.3
In this chapter
Functions a Mapping
Pupils should be able to:
• represent simple
functions using words,
symbols and mappings 3.3.1 Functions
• use letters to represent
unknown numbers or A functional relationship exists between paying for petrol and the litre. The
variables more litres of petrol we buy, the more we have to pay. We can find the value
of one variable {such as the petrol price) when we know the value of the other
variable (the number of litres needed).
The relationship between two variables in which each value of the first variable
corresponds to exactly one value of the other variable is called a function. It is
like a function machine that performs one or more mathematical operations on
a number entered to produce an answer.
Check My Input
Understanding This function machine
adds 2 to any number (1) to
give the number (3) that comes
Write down the function
out of the machine.
in the function machine.
Output
The numbers that are put into the function machine are called the input
numbers. The numbers that come out of the function machine are called the
output numbers.
Some function machines can perform more than one operation.
This function machine takes
in a number (5) and multiplies input
Output
by 2 to get 10, and then
adds 3 to get 13.
So, the output is 13 when the
input is 5.
Output
Input Output
We can draw a map
to show the function 4
'multiply the input 7
number by 2 and
8
then add 3'.
10
UNITS Introduction to Algebra and Equations
