1. 27/01/2015 Presented By J. Mills-Dadson 1
Linear Graphs
Objectives: by the end of the lesson, students
should be able to:
generate coordinate pairs that satisfy a simple linear rule
plot the graphs given explicitly in terms of x.
Success Criteria: students should be able to
generate coordinate pairs from E.g.: y = 2x
 Keywords: substitute, intercept, gradient, origin,
parallel

2. 27/01/2015 Presented By J. Mills-Dadson 2
Linear Graphs
Linear graphs are straight lines
The rule connecting x and y coordinates is of the
form y = mx + c
‘m’ is the gradient : how flat or how steep the
graph should be
‘c’ is the intercept: where the graph crosses the
y-axis
The meeting points of the x - axis and y – axis is
called the origin

3. 27/01/2015 Presented By J. Mills-Dadson 3
Linear Graphs
x 0 1 2 3
y
1) Let us start with simple rule,
y = x
0 1 2 3
x 0 1 2 3
y
2) Now let’s y = x + 2
2 3 4 5
x 0 1 2 3
y
Now let’s y = 2x + 2
2 4 6 8
Let’s plot the coordinates of the
first two rules on one grid.
y
1 0
9
8
7
6
5
4
3
2
1
x0 432-3 -2 -1 1 5
-1
-2
-3
y
1 0
9
8
7
6
5
4
3
2
1
x0-3 -2 -1 1 2 3 4 5
-1
-2
-3
Join the
points to draw
the graph

4. 27/01/2015 Presented By J. Mills-Dadson 4
Linear Graphs
x 0 1 2 3
y
2) Now let’s y = x + 2
2 3 4 5
x 0 1 2 3
y
Now let’s y = 2x + 2
2 4 6 8
Let’s plot the coordinates of the
These two rules on one grid.
y
1 0
9
8
7
6
5
4
3
2
1
x0 432-3 -2 -1 1 5
-1
-2
-3
y
1 0
9
8
7
6
5
4
3
2
1
x0-3 -2 -1 1 2 3 4 5
-1
-2
-3
Join the
points to
draw the
graph
What can you say about the slope and
where the cross the y – axis?