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.

3729 questions
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Determine if a number n is a power

What would be an efficient algorithm to determine if $n \in \mathbb{N}$ can be written as $n = a^b$ for some $a,b \in \mathbb{N}, b>1$? So far, I've tried: def ispower(n): if n<=3: return False LIM = math.floor(math.log2(n)) for…
Ricardo
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What does it mean to put $\sqrt{\phantom{-v}}$ alone below a square rooted expression?

In Yaremenko's paper here, on the 5th page of the pdf, which is page ten, in section IV, he uses a square root symbol alone under $\sqrt{-g}$ and $\sqrt {-g} \, dV$. What does this mean?
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Finding $x$ when $\sqrt{3x - 4} + \sqrt[3]{5 - 3x} = 1$

Find $x$ if $\sqrt{3x - 4} + \sqrt[3]{5 - 3x} = 1.$ I was thinking of trying to substitute some number $y$ written in terms of $x$ than solving for $y$ to solve for $x.$ However, I'm not sure what $y$ to input, so can someone give me a hint?
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Why isn't the square root of a number such as $\sqrt 9 = \pm3$?

This is a really basic question and to be honest I feel ashamed to be asking this when I'm in precalculus and trigonometry right now. When I was younger, I was taught that $\sqrt{x^2}$ was equal to $\pm x$. However, during this course I've inputted…
rosa
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Square-root equation

Solve square-root equation: $\left (\sqrt{5+2\sqrt{6}} \right )^x+\left (\sqrt{5-2\sqrt{6}} \right )^x=10$ $\left (\sqrt{5+2\sqrt{6}} \right )^x+\left (\sqrt{5-2\sqrt{6}} \right )^x=10\\ \left (\sqrt{\left (\sqrt{3}+\sqrt{2} \right )^2}…
vmahth1
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For $x\geq 0$, is $\sqrt{x}$ the magnitude of $x^{1/2}$?

Motivation \begin{align} 4^{1/2} &= \begin{cases} \left(2^2\right)^{1/2}\\ \left(\left(-2\right)^2\right)^{1/2} \end{cases} \\ &= \begin{cases} 2\\ -2 \end{cases} \end{align} And $\sqrt{4}=2$ (by…
Display Name
  • 2,715
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Simplify $B=\sqrt{x^2} - x$

I have to simplify the following expression: $B=\sqrt{x^2} - x$ The only thing that I can do is: $\sqrt{a^2}=|a|$, thus $B=|x|-x$. Is that enough?
Valeri
  • 167
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Evaluating expression with Integer part and Fraction part of a nested radical

Let $$A= \sqrt{93+28\sqrt{11}}$$ if $B$ is the integer part of $A$ and $C$ is the fraction part of $C$, what is the value of $$B+C^2$$ I tried manipulating it by setting $$ A=B+C$$ but I can't transform it into the expression, do I need…
SuperMage1
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Highest value expressed as $a + b\sqrt{2}$ less than a given value

I would like to find the highest number of the form $a + b\sqrt{2}$ less than a given value, where $a$ and $b$ are nonnegative integers. For example, if the value was $8.4$, then just trying all possible combinations less than $8.4$ would yield $a…
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Roots Across the Complex Numbers

Why is it the case that an even root (square root, quartic, etc) can be positive or negative across the complex numbers, but is limited to postive in the reals? Is there a good mathematical reason for this, or is it simply notation?
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Computing $\sqrt[4]{28+16 \sqrt 3}$

I want to compute following radical $$\sqrt[4]{28+16 \sqrt 3}$$ For that, I first tried to rewrite this in terms of exponential. $$(28+16\cdot 3^{\frac{1}{2}})^{\frac{1}{4}}$$ We know that $ 28 = 2 \cdot 7^{\frac{1}{2}}$ $$(2 \cdot…
Melz
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Find the value of a 5th-root expression.

Simplify and find the value of the expression: $$\sqrt[5]{\frac{123+\sqrt{15125}}{2}}+\sqrt[5]{\frac{123-\sqrt{15125}}{2}}.$$ I tried to rationalise it. It was of no use..
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How to simplify an expression

I have an expression: $$\frac{\sqrt{6} + 1}{6} - \frac{\sqrt{10-4\sqrt{6}}}{6}$$ and it seems like it must be equal to $\frac{1}{2}$. How could i simplify this?
Dmitrii
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Checking whether $5876432$ is a perfect square or not

I was solving a question and ended up with the expression $\sqrt{5809}$ and seeing this expression started a question in my head:If numbers upto $700$ are given to me i can immediately see them and tell whether they are perfect squares or not;but…
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Square root of radicals

Find the square root of $4^{1/3}+16^{1/3}+1$. I tried to solve by supposing the square root to be $x$ and then cubing both sides but it didn't work. I do not need exact value. By hit and trial I have seen that answer should involve $2^{1/3}+1....$…
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