Steply

Simplify (1 - 1/x)/(3/x)

Step by step, with the reason for every step · Complex fractions · Algebra 2

Step by step

The question

Question: simplify this fraction.

On top: 1 − 1 over x.

At the bottom: 3 over x.

A fraction with fractions inside is called a complex fraction.

1 − 1x3x

1 Find the common bottom

The small fraction has the bottom x.

The smallest thing they all go into is x.

small bottoms: x
common bottom: x

Careful!

We multiply EVERY part by x, also the part with no small bottom.

Leaving it out is the usual mistake.

Careful: every part times x, the whole numbers too

2 Times x on top and bottom

x/x is 1.

Times 1 does not change the value.

xx = 1

We multiply the top and the bottom by x.

Then the small fractions go away.

= x × (1 − 1x)x × (3x)

3 Multiply every part

Every part times x.

x times 1 is x.

x times 1/x: the bottom x goes into x, so we get 1.

x × 1 = x
x × (−1x) = −1
x × 3x = 3

So we get (x − 1)/3.

No more small fractions!

= x − 13

4 Simplify

Is there a number or an x that goes into every part, top and bottom?

No.

So it is already simple.

So the answer is (x − 1)/3.

nothing goes into every part

One more thing: no bottom can be 0.

So x can't be 0.

x ≠ 0

5 Check

Let's check with a number: x = 2.

In the question, the long way: the top is 1/2, the bottom is 3/2.

x = 2: top 1 − 12 = 12, bottom 32 = 32

Top divided by bottom: 1/3.

question: 12 ÷ 32 = 13

Our answer with x = 2 gives 1/3 too.

It works!

answer: 2 − 13 = 13

Let's look back.

First: find the common bottom.

Then: times x on top and bottom.

Then: multiply every part.

Then: simplify.

Last: check.

Answer
nothing goes into every part

Your turn

Try this one yourself, then check:

simplify (1 − 5x) ÷ (3x)
Show the answer
x − 53

More from Complex fractions

The whole lesson: Complex fractions →