AQA_Bk1_chap13_Layout 1 21/01/2010 09:50 Page 406
CHAPTER 13: Algebra: Graphs
EXAMPLE 4
Use the flow diagram below to draw the graph of y = 4x – 1.
0, 1, 2, 3, 4
x
?, ?, ?, ?, ?
×4
–1
?, ?, ?, ?, ?
y
y
15
Now enter the values in a table.
x
y
0
0
1
0
2
0
3
0
4
0
The table becomes:
x
y
0
–1
1
3
2
7
0
–1
y = 4x – 1
y
3
11
4
15
x
4
15
14
13
So, the coordinates are:
(0, –1), (1, 3), (2, 7), (3, 11), (4, 15)
Plot these points and join them up to
obtain the graph shown on the right.
This is the graph of y = 4x – 1.
12
11
10
9
8
7
6
5
4
3
2
1
0
–1
1
2
3
4
x
Always label your graphs. In an examination, you may need to draw more than one graph on
the same axes. If you do not label your graphs you may lose marks.
406 UNIT 2