# Rules for radicals [Solved!]

**Rika** 28 Nov 2015, 05:44

### My question

Is it true that the rules for radicals only apply to real numbers? Because `\sqrt {-2}\times \sqrt {-18}` is not equal to `\sqrt{-2 \times -18}`?

### Relevant page

3. Simplest Radical Form

### What I've done so far

Read over the page and done the examples.

X

Is it true that the rules for radicals only apply to real numbers? Because `\sqrt {-2}\times \sqrt {-18}` is not equal to `\sqrt{-2 \times -18}`?

Relevant page
<a href="/exponents-radicals/3-simplest-radical-form.php">3. Simplest Radical Form</a>
What I've done so far
Read over the page and done the examples.

## Re: Rules for radicals

**Newton** 29 Nov 2015, 09:17

Hi Rika

Thanks for your mail.

Yes, you are right. Ex 2(a) and 2(b) at the bottom of this page

indicate what you are saying:

1. Basic Definitions of Complex Numbers

Regards

X

Hi Rika
Thanks for your mail.
Yes, you are right. Ex 2(a) and 2(b) at the bottom of this page
indicate what you are saying:
<a href="/complex-numbers/1-basic-definitions.php">1. Basic Definitions of Complex Numbers</a>
Regards

## Re: Rules for radicals

**RikaAlpha** 21 Apr 2016, 11:42

Hello Murray,

This discussion from last year. Should school text books not mention the restrictions when working with "laws of exponents"? For example,

`(a^m)^n=a^(mn)` only when a > 0 and m and n integer?

`[(-1)^2]^(1/2) != (-1)^(2xx 1/2 )`

as is mentioned in this book:

Everything Maths and Science

but I do not see it in most school textbooks?

regards

Rika

X

Hello Murray,
This discussion from last year. Should school text books not mention the restrictions when working with "laws of exponents"? For example,
`(a^m)^n=a^(mn)` only when a > 0 and m and n integer?
`[(-1)^2]^(1/2) != (-1)^(2xx 1/2 )`
as is mentioned in this book:
<a href="http://www.everythingmaths.co.za/maths/grade-10/03-exponentials">Everything Maths and Science</a>
but I do not see it in most school textbooks?
regards
Rika

## Re: Rules for radicals

**Murray** 20 May 2016, 02:51

Hi Rika

Sorry - I thought I responded to this already, but realised I wanted to make sure IntMath stated the correct conditions. It didn't, but it does now in the summary on this page: Numbers

Thanks for alerting us to this.

Regards

Murray

X

Hi Rika
Sorry - I thought I responded to this already, but realised I wanted to make sure IntMath stated the correct conditions. It didn't, but it does now in the summary on this page: <a href="/numbers/4-powers-roots-radicals.php">Numbers</a>
Thanks for alerting us to this.
Regards
Murray

You need to be logged in to reply.