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Solve |x - 5| <= 1

Step by step, with the reason for every step · Absolute value inequalities · Algebra 1

Step by step

The question

Question: solve |x − 5| ≤ 1.

|x − 5| ≤ 1

1 Draw the distance

2 Write it without bars

So x − 5 is between −1 and 1: −1 ≤ x − 5 ≤ 1.

Now x is in the middle.

−1 ≤ x − 5 ≤ 1

3 Remove the − 5

We want x by itself.

The − 5 is in the way.

To remove − 5, we add 5.

We do it to all three parts.

Why all three?

The signs compare the three parts.

If we change only one part, the answer can change.

−1 + 5 ≤ x − 5 + 5 ≤ 1 + 5

− 5 and + 5 make zero.

Cross them out.

−1 plus 5 is 4.

1 plus 5 is 6.

−1 + 5 = 4
1 + 5 = 6

Now we have 4 ≤ x ≤ 6.

So x is between 4 and 6: 4 ≤ x ≤ 6.

4 ≤ x ≤ 6

4 Show it on a number line

Books also write the answer like this.

It is called interval notation.

A square bracket means the end is in, like the filled circle.

interval: [4, 6]

5 Check

Let's test one number from the answer: 6.

We put it in the question.

The inside is 1, and the bars make it 1.

x = 6: |6 − 5| = |1| = 1

1 is less than or equal to 1.

True!

So the answer works.

1 ≤ 1

Let's look back.

First: draw the distance.

Then: write it without bars.

Then: remove the − 5.

Then: show it on a number line.

Last: check.

Answer
4 ≤ x ≤ 6

Your turn

Try this one yourself, then check:

Solve |x − 10| ≤ 1
Show the answer
9 ≤ x ≤ 11

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