Steply

Simplify 4th root of 32

Step by step, with the reason for every step · Higher roots · Algebra 1

Step by step

The question

Question: simplify the 4th root of 32.

4√32

The small 4 says how many times.

The 4th root of 32 asks: which number, times itself 4 times, makes 32?

? × ? × ? × ? = 32

1 Find the biggest 4th power

4th powers are a number times itself 4 times.

2 × 2 × 2 × 2 is 16.

4th powers: 24 = 16

We try the biggest first.

Does 16 go into 32?

Yes: 32 divided by 16 is 2.

32 ÷ 16 = 2 ✓

Careful!

4 is a square, not a 4th power.

The 4th root of 4 is not 2.

We need a number times itself 4 times.

Careful: not 4√4 × 8 = 24√8 ✗

2 Split the root

So 32 is 16 times 2.

We write it under the root.

= 4√16 × 2

Rule: a root over a times can be split into two roots.

4√a × b = 4√a × 4√b

So it is the 4th root of 16 times the 4th root of 2.

= 4√16 × 4√2

The 4th root of 16 is 2, because 2 × 2 × 2 × 2 is 16.

2 × 2 × 2 × 2 = 16

We write 2 in place of the 4th root of 16.

= 2 × 4√2

We leave out the times sign.

2 has no 4th power in it, so we are done.

So the 4th root of 32 = 2 times the 4th root of 2.

= 24√2

3 Check

Let's check: we take the answer to the power 4.

The 4th root of 2 to the power 4 is just 2.

(24√2)4 = 2 × 2 × 2 × 2 × 2

2 × 2 × 2 × 2 is 16.

Times 2 is 32.

We get 32 back.

So the answer is right!

= 16 × 2 = 32

Let's look back.

First: find the biggest 4th power.

Then: split the root.

Last: check.

Answer
= 24√2

Your turn

Try this one yourself, then check:

Simplify 4√112
Show the answer
24√7

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