Questions tagged [radicals]

For questions involving radical of numbers or radical of expressions (i.e. numbers/expressions raised to the power of a fraction).

A radical expression is any mathematical expression containing a radical symbol $~(√~)~$.

Many people mistakenly call this a 'square root' symbol, and many times it is used to determine the square root of a number. However, it can also be used to describe a cube root, a fourth root, or higher.

When the radical symbol is used to denote any root other than a square root, there will be a superscript number in the $'V'$-shaped part of the symbol. For example, $~3\sqrt{8}~$ means to find the cube root of $~8~$. If there is no superscript number, the radical expression is calling for the square root.

The term underneath the radical symbol is called the radicand.

Steps required for Simplifying Radicals:

Step $~1~$: Find the prime factorization of the number inside the radical. Start by dividing the number by the first prime number $~2~$ and continue dividing by $~2~$ until you get a decimal or remainder. Then divide by $~3,~ 5,~ 7,~$ etc. until the only numbers left are prime numbers. Click on the link to see some examples of Prime Factorization. Also factor any variables inside the radical.

Step $~2~$: Determine the index of the radical. The index tells you how many of a kind you need to put together to be able to move that number or variable from inside the radical to outside the radical. For example, if the index is $~2~$ (a square root), then you need two of a kind to move from inside the radical to outside the radical. If the index is $~3~$ (a cube root), then you need three of a kind to move from inside the radical to outside the radical.

Step $~3~$: Move each group of numbers or variables from inside the radical to outside the radical. If there are nor enough numbers or variables to make a group of two, three, or whatever is needed, then leave those numbers or variables inside the radical. Notice that each group of numbers or variables gets written once when they move outside the radical because they are now one group.

Step $~4~$: Simplify the expressions both inside and outside the radical by multiplying. Multiply all numbers and variables inside the radical together. Multiply all numbers and variables outside the radical together.

A closely related tag is the tag.

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Is √n^x irrational, if x is an odd integer?

I am assuming that, n is a prime number, because you can express composite numbers to prime by enlarging the exponent. a = nn^x-1 = n I don't know how to prove or disprove it, but if x is odd then, a is always multiplied by a prime number, which…
Newbie
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Why does the square root function produce a negative value here?

We know that the square root function ($\sqrt{}$) always produces non-negative numbers. Why then, does the square root function produce a negative value here? $$x^2=4$$ $$\implies \pm \sqrt{x^2}=2$$ $\implies \sqrt{x^2}=2...(i)$, or, $\implies…
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If $\sqrt{x^2} = \sqrt{16}$, then does $x= \pm\sqrt{16}$?

I am confused about how square roots work. I know the square root function gives the principal square root, but I'm confused because if we just take the positive number, I get $x = 4$, which doesn't include the $x=-4$ case.
beginner
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Value Radical problem

Calculate the value of the radical: $$\left[\sqrt[{\sqrt[\sqrt3]{\sqrt3}}]{(3 \sqrt 3)^{ \sqrt[\sqrt3]{\sqrt3^{\sqrt3+1}}}}\right]^{\sqrt 3}$$ What is the tip to solve this problem? I think $(3\sqrt{3})^{9}$ is the answer Attemp: I started thinking…
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Solve for x Given Two Square Roots: Algebra Problem

I am trying to solve for all real numbers for $x$ given $5=\sqrt{9-x^2}+\sqrt{16-x^2}$. The answer is that $x=\pm \frac{12}{5}$. I am looking for a clean way to do it. I am stumped, and I feel like I am missing something about conjugates here.
W. G.
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need help simplifying this radical $\sqrt[35]{128y^{42}}$

I am trying to figure out how to get to the solution below but have having difficulty. Can someone explain how to get to the solution. $$\sqrt[35]{128y^{42}}$$ This is the answer but I can't figure out how to get it. $$2^{\frac15}y^{\frac65}$$
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How do I reduce the index of a radical $\sqrt[9]{64a^6b^{12}}$?

$\sqrt[9]{64a^6b^{12}}$ It doesn't have to be the answer, just tell me what I should do
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Why $\sqrt {xy} = \sqrt x \sqrt y$ and same for division

Why $\sqrt {xy} = \sqrt x \sqrt y$ and same for division? I found question like these on website but I don't anything about precalculus and not even whole algebra so I want to know the proof with basic concepts that can explain it.
Mohd Saad
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Simplify $\sqrt{5-2\sqrt{6}}$

So the given expression $\sqrt{5-2\sqrt{6}}$ has the same answer as $\sqrt{3}-\sqrt{2}$ Which is equal to $0.31783724...$ How do I simplify the 1st equation into the 2nd equation?
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Comparing complex roots with permitted real roots

In this question, the right answer is B. While we get B regardless of whether we consider one root or both roots for the third equation, my question pertains to whether we should consider the second root, that is, $–2$. $–2$ as a root gives…
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How to simplify surd expressions such as this?

I am having trouble with questions like these: $$\sqrt{x-y\sqrt z}$$ Or as an example: $$\sqrt{17-12\sqrt2}$$ I cannot see how to go about this. I have tried squaring the expression, which ends up giving $\sqrt{289}-\sqrt{288}$, but I do not know…
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Help getting the result $\sqrt{n}-\sqrt{n-\frac{1}{4}}\approx\frac{1}{8\sqrt{n-\frac{1}{8}}}$

I have checked "by hand" that $$\sqrt{n}-\sqrt{n-\frac{1}{4}}\approx\frac{1}{8\sqrt{n-\frac{1}{8}}}$$ However, I do not manage to prove the result. Any help would be welcomed!
Juan Moreno
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Simplifiy radicals

I took an algebra exam today and came across this problem Simplify: $ 5\sqrt{2t} - 7\sqrt{4t} + 10\sqrt{2t} $ A. $\sqrt{t}$ B. $\sqrt{2}$ C. $\sqrt{2t}$ D. $15\sqrt{2t} - 7\sqrt{4t} $ Two different approaches give two different results? I did…
bau8312
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Is the $\sqrt{(-10)^2}$ equivalent to $-10$ or $10$?

Is $\sqrt{(-10)^2}$ equivalent to $-10$ or $10$, or is it equivalent to only one among the two? Since $\sqrt{(-10)^2} = \sqrt{100}$ and $\sqrt{100} =$ $-10$ or $10$. Using this solution, it can be equivalent to either the two answers. But using…
AYA
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Why is $\sqrt{ab}$ = $\sqrt{a}\sqrt{b}$ not true when a and b are both negative?

Apparently $\sqrt{ab}$ = $\sqrt{a}\sqrt{b}$ is only true if a and b are both positive or if a is negative and b is positive or if a is positive and b is negative. In other words, a and b can't both be negative. Is it possible to algebraically prove…
Dom Turner
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