### 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}?

### 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

What I've done so far

Read over the page and done the examples.

Continues below

Hi Rika

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

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

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 &gt; 0 and m and n integer?
[(-1)^2]^(1/2) != (-1)^(2xx 1/2 )
as is mentioned in this book:
but I do not see it in most school textbooks?
regards
Rika

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