Step by step
The question
Question: graph y = 3x − 1 using a table of values.
We pick some x values.
We work out y for each one.
Each x and y make a point.
1 Choose x values
We pick three easy x values: −1, 0 and 1.
Two points make a line.
The third one checks them.
2 Work out y
Put x = −1 in.
We get y = −4.
Now x = 0 in.
We get y = −1.
Now x = 1 in.
We get y = 2.
3 Plot the points
Draw the grid.
Each column is a point: x on top, y under it.
The first one is (−1, −4).
Put a dot.
Careful!
The x on top comes first, then the y under it: (−1, −4).
Many people write the y first.
(0, −1).
Dot.
(1, 2).
Dot.
4 Draw the line
The three dots line up.
Join the dots with a straight line that keeps going both ways.
Go right 1,
up 3: the slope is 3.
5 Check
Let's check with one more x: x = 2.
We get y = 5.
The point (2, 5) is on our line.
So the graph is right!
Let's look back.
First: choose x values.
Then: work out y.
Then: plot the points.
Then: draw the line.
Last: check.