# $\sqrt[4] {81}$ (find the root if it's a real number)

$\sqrt[5]{(-5)^5}$

Simplify the root:

$\sqrt[4]{x^4}$

$-\sqrt[3]{x^9}$

$-\sqrt{x^{18}}$

Thank you to everyone who replies <3

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By index $4 \sqrt{81}$ do you mean the fourth root of $81, \sqrt[4]{81}$ To write roots in $\LaTeX$, which are easier to read, you enclose in dollar signs \sqrt[index]{number to take the root of} so to get $\sqrt[4]{81}$ I wrote \sqrt[4]{81} – Ross Millikan May 1 '13 at 21:37
I believe that I do. I'm sorry, I must seem like an invalid. – user75437 May 1 '13 at 21:38
It said "index" in my book, so I assumed that was what it was called. – user75437 May 1 '13 at 21:39
oh sweet. I only learned the symbol for square root from imgur. lol. Thank you. – user75437 May 1 '13 at 21:40
No, many people don't know $\LaTeX$, but it makes math much easier to read. Here is a place to start. The point about right-clicking and picking Show Math as -> TeX Commands is a great way to learn. – Ross Millikan May 1 '13 at 21:41

Hint: Do you know that powers and roots are inverse functions, so $\sqrt [a]b=b^{\frac 1a}$? Then do you know a law of exponents about $(a^b)^c$? These will take you far.

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The teacher that I have isn't the greatest. When I was attempting to learn factoring and the distributive prop. he told us NOT to use FOIL. It made life pretty hard, as that's how I learned from the start. He just has a different teaching style I guess. – user75437 May 1 '13 at 21:52

Brace yourselves, for square roots are coming..

Assuming that the question is wether

$$\sqrt[5]{(-5)^5}$$

is a real number or not, note that

$$(-5)^5=(-1\cdot5)^5=(-1)^5 5^5=-5^5$$

$$\sqrt[5]{(-5)^5}=\sqrt[5]{-1}\sqrt[5]{5^5}$$

so it is not real.

For the simplifications note that

$$\sqrt[n]{a}=(a)^{1/n}$$

and

$$(a^{n})^{m}=a^{nm}$$

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So any negatives are not real numbers? these square roots are dark and full of terrors – user75437 May 1 '13 at 23:48
@Nivalth $(-1)$ doesn't have a real fifth root?! You may want to look at what you wrote again... – RecklessReckoner May 2 '13 at 3:19