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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I would like to know why the result of this exercise is "10x"

The resolution of this exercise $(2\sqrt{x})*(5\sqrt[3]{x})$ is 10x. But I can't understand the steps to reach that result, since when I try to solve it, I get to: $(2\sqrt{x})\cdot(5\sqrt[3]{x})$ $5 \cdot 2$ $(\sqrt{x}) = x ^ \frac{1}{2}$ and…
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Solution to this radical equation?

Is $-1$ a solution to $\sqrt{4x+5}=x$ ? Why or why not?
P97
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Help solve this equation: $\sqrt{3x-4}+\sqrt[3]{5-3x}=1$

$\sqrt{3x-4}+\sqrt[3]{5-3x}=1$ Find x. I've been assigned this question for homework in an online class and I'm a little bit stuck. I tried defining a variable $a=3x-9/2$ but it didn't really bring me anywhere. Hints would be greatly appreciated!
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Questioning the rules of radicals

Does an absolute value symbol need to be included every time a radical with a variable expression has an even index? I understand that in some cases there needs to be a absolute value symbol just in case the variable is equal to a negative number…
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roots: square roots, cube roots, x^1/4, x^1/5

I was having confusion over the concepts of roots. My confusion begins as: I know that if $x^{1/n}=y$ then $y^n=x$ must be true. Case 1: With square roots, let's take $y=4^{1/2}$ We know $y=2$ is a solution as $2^2=4$, but $y=-2$ must also be a…
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Simplify $D=\sqrt{x^2}+\sqrt{x^2-2x+1}$

I have this expression, and I have to simplify it: $D=\sqrt{x^2}+\sqrt{x^2-2x+1}$ Answer: $1)$ If $x<0, D=1-2x$, $2)$ if $0\le x<1, D=1;$ $3)$ if $x>1, D=2x-1$. I received $|x-1| + |x|$, but I am not sure how to continue, and I have problems…
Valeri
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How to stop graph from appearing in extra quadrants

I was simplifying the equation, $\sqrt{(x^2 + x)}xy = 5$, to, $\sqrt{(x^4 y^2 + x^3 y^2)} = 5$, using $\sqrt{(x)} x = \sqrt{(x^3)}$ but the graph appeared in all quadrants not just two and four. Can anyone explain why this happens and how to fix it?
L. Kohler
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$3 \times 8$ Array Problem: Finding the Longest Line Containing Exactly 3 Dots

In the $3 \times 8$ array, the dots are evenly spaced horizontally and vertically with each dot 1 cm from the nearest neighboring dots. In simplest radical form, what is the number of units in the length of the longest segment containing exactly 3…
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Square root and Cube root in the same equation

In a recent test I took, I received a question in an awkward form: $$\sqrt y-\sqrt[3]{1000-y}=16$$ How would I go about solving this?
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Square-root equation with no solutions

There is an equation given: $${\sqrt {3x-7}} + {\sqrt {2x-1}} = 0$$ Solving it algebraically: $${(\sqrt {3x-7})^2} + {(\sqrt {2x-1})^2} = 0$$ $$ 3x-7 + 2x-1 = 0 $$ $$ 5x = 8 $$ $$ x = \frac{8}{5} $$ But doing it $${\sqrt {3x-7}} = {-\sqrt…
Jakub
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Evaluating $\sqrt{2 + \sqrt{2 + \sqrt{2 + \sqrt{2 + \cdots }}}}$

I saw this problem in a math competition and I have no idea how to solve it: $$\sqrt{2 + \sqrt{2 + \sqrt{2 + \sqrt{2 + \cdots }}}}$$
Obsculyze
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Evaluate $( \sqrt{288} + \sqrt{119})^{3/2} - ( \sqrt{288} - \sqrt{119})^{3/2}$

I need to find the value of $$( \sqrt{288} + \sqrt{119})^{3/2} - ( \sqrt{288} - \sqrt{119})^{3/2}$$ I tried using the identity $a^{3} - b^{3}$ but couldn't reach very far and got stuck.
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Simplify a square root by factoring it for sum-product method

I ran into a mathematical problem which I guess I can simplify by product-sum factoring, I learned this approach while studying in Kumon, but I am afraid I have forgotten. This is the expression: $\sqrt{10 - 2 \sqrt{ 21 } }.$ Notice that $7\cdot…
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Put the $\sqrt[n]{n}$ numbers in to an increasing order

I had a test today and there was an extra problem I couldn’t solve. Put the $\sqrt[2]{2}, \sqrt[3]{3}, \dots, \sqrt[100]{100}$ numbers in to an increasing order. I just have no idea. I can handle the numbers $\sqrt[2^k]{2^k}$ numbers, but I can’t…
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Simple equation with square root $2x-6-4\sqrt x=0$

Good evening to everybody, I have a doubt about the following simple equation: $$2x-6-4\sqrt x=0$$ I know that x should equal to $9$. But how do I arrive to this result? In particular, my difficulty is to deal with square root. Thanks in advance!