Page 65 - Math Smart - 7
P. 65
.3.2 Mapping diagrams
A mapping diagram shows a function. Input Output
4 \
The following mapping diagram tells us that U) >. 11
4 maps onto 11, 7 — 17
7 maps onto 17,
8 >■ 19
8 maps onto 19,
10 23
y
J
10 maps onto 23 in this function. V ^
The function that maps the input values onto those X -^2x + 3
output values is written as a: ^ Ix + 3.
We say that: 'x is mapped onto Ix + 3'.
Example 1
Find the output number of this function machine.
6 x3 +
5
Solution
We can use the function machine to do the following calculations.
6 X 3 = 18
18 + 5 = 23
So, the output number is 23.
Find the input number of this function machine.
+ 2 -3 6
Solution
To find the input number, we write the inverse operation below the
boxes.
The inverse of 'dividing by 2' is 'multiplying by 2' and the inverse of
'subtracting 3' is 'adding 3'.
>-<±i
18 2 -3 0
xT)<—(TI
So, the input number is 18.
o
