Steply

Graph 2x + 4y = 6

Step by step, with the reason for every step · Graphing Ax + By = C · Algebra 1

Step by step

The question

Question: graph 2x + 4y = 6.

2x + 4y = 6

Every point on the x-axis has y = 0.

Every point on the y-axis has x = 0.

on the x-axis: y = 0
on the y-axis: x = 0

1 Cross the x-axis

On the x-axis, y = 0.

Put 0 in place of y.

2x + 4 × 0 = 6

4 times 0 is 0.

Adding 0 changes nothing.

2x = 6

2x means 2 times x.

We want just x.

To remove times 2, we divide by 2.

We do it on both sides, so they stay equal.

2x2 = 62

2 divided by 2 is 1.

So just x is left.

6 divided by 2 is 3.

62 = 3

So x = 3.

x = 3

So the line crosses the x-axis at (3, 0).

This point is called the x-intercept.

→ (3, 0)

2 Cross the y-axis

On the y-axis, x = 0.

Put 0 in place of x.

2 × 0 + 4y = 6

2 times 0 is 0.

0 plus 4y is just 4y.

4y = 6

4y means 4 times y.

We want just y.

To remove times 4, we divide by 4.

We do it on both sides, so they stay equal.

4y4 = 64

4 divided by 4 is 1.

So just y is left.

We can make 6/4 simpler.

It is the same as 3/2.

That is 1.5.

64 = 32 = 1.5

So y = 1.5.

y = 1.5

So the line crosses the y-axis at (0, 1.5).

This point is called the y-intercept.

→ (0, 1.5)

3 Draw the line

Draw the grid.

The x-axis goes across.

The y-axis goes up and down.

They meet at 0.

That point is called the origin.

Put the two points on the grid: (3, 0)

and (0, 1.5).

Join the dots with a straight line.

It keeps going both ways.

4 Check

Let's check with another point on the line: (1, 1).

It sits on a grid corner.

Put x = 1 and y = 1 into 2x + 4y.

2(1) + 4(1) = 2 + 4 = 6

We get 6, the same as the right side.

So the line is right!

Let's look back.

First: cross the x-axis.

Then: cross the y-axis.

Then: draw the line.

Last: check.

Answer
y = 1.5

Your turn

Try this one yourself, then check:

Graph 3x + 4y = 18
Show the answer
crosses at (6, 0) and (0, 4.5)

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