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Simplify 4^(3/2)

Step by step, with the reason for every step · Rational exponents · Algebra 1

Step by step

The question

Question: work out 4^(3/2).

4^(3/2)

A fraction power has two jobs.

The bottom number, 2, says which root: the square root.

The top number, 3, says which power.

For the square root, the small 2 is not written.

a^(m/n) = (n√a)m

Careful!

The power is not times.

4 times 3/2 is a different number.

Careful: not 4^(3/2) = 4 × 32 ✗

1 Take the root

The bottom is 2: the square root of 4.

The top is 3: to the power 3.

We take the root first.

It keeps the numbers small.

= (√4)3

√4 is 2, because 2 × 2 is 4.

2 × 2 = 4

We write 2 in place of √4.

= 23

2 Take the power

2 to the power 3 is 2 × 2 × 2.

That is 8.

2 × 2 × 2 = 8

So 4^(3/2) = 8.

= 8

3 Check

Let's check the other way: the power first, then the root.

4 to the power 3 is 64.

Other order: 43 = 64

The square root of 64 is 8, because 8 × 8 is 64.

We get 8 again.

But the numbers were bigger.

So root first is easier.

And the answer is right!

√64 = 8, 8 × 8 = 64

Let's look back.

First: take the root.

Then: take the power.

Last: check.

Answer
= 8

Your turn

Try this one yourself, then check:

Work out 16^(3/4)
Show the answer
8

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