No.048 Graphs of Direct Proportion

POINT

① Substitute x-values into y = ax to make a table of corresponding y-values.
② Plot the points and draw a straight line through the origin (0, 0).

Example

Complete each table and draw the graph.

① y = 2x

x	-2	-1	0	1	2
y	?	?	?	?	?

② y = −1/2 x

x	-4	-2	0	2	4
y	?	?	?	?	?

Watch. Think. Try.

Try it yourself.

Complete each table first. Then plot the points and draw the straight line through them.

Complete the table and draw the graph of y = 3x .

x	-1	0	1
y	?	?	?

Table and graph

x	-1	0	1
y	-3	0	3

Complete the table and draw the graph of y = −2x .

x	-2	-1	0	1	2
y	?	?	?	?	?

Table and graph

x	-2	-1	0	1	2
y	4	2	0	-2	-4

Complete the table and draw the graph of y = 1/2 x .

x	-4	-2	0	2	4
y	?	?	?	?	?

Table and graph

x	-4	-2	0	2	4
y	-2	-1	0	1	2

Complete the table and draw the graph of y = −1/3 x .

x	-3	0	3
y	?	?	?

Table and graph

x	-3	0	3
y	1	0	-1

Complete the table and draw the graph of y = 4x .

x	-1	0	1
y	?	?	?

Table and graph

x	-1	0	1
y	-4	0	4