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Graph y = 1/3x - 2 using a table

Step by step, with the reason for every step · Graphing with a table · Algebra 1

Step by step

The question

Question: graph y = (1/3)x − 2 using a table of values.

y = 13x − 2

We pick some x values.

We work out y for each one.

Each x and y make a point.

1 Choose x values

The slope has 3 at the bottom.

So we pick x values that 3 goes into: −3, 0 and 3.

Then y comes out whole.

x = −3, 0, 3: 3 goes in

Two points make a line.

The third one checks them.

2 Work out y

Put x = −3 in.

We get y = −3.

x = −3: y = 13(−3) − 2 = −1 − 2 = −3
−3

Now x = 0 in.

We get y = −2.

x = 0: y = 13(0) − 2 = 0 − 2 = −2
−2

Now x = 3 in.

We get y = −1.

x = 3: y = 13(3) − 2 = 1 − 2 = −1
−1

3 Plot the points

Draw the grid.

Each column is a point: x on top, y under it.

The first one is (−3, −3).

Put a dot.

(0, −2).

Dot.

Careful!

The x on top comes first, then the y under it: (0, −2).

Many people write the y first.

Careful: not (−2, 0) ✗

(3, −1).

Dot.

4 Draw the line

The three dots line up.

Join the dots with a straight line.

It keeps going both ways.

5 Check

Let's check with one more x: x = 6.

We get y = 0.

x = 6: y = 13(6) − 2 = 2 − 2 = 0

The point (6, 0) 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.

Answer
−1

Your turn

Try this one yourself, then check:

y = 23x − 4
Show the answer
(−3, −6), (0, −4), (3, −2)

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