Square Root of a Negative Number

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Square Root of a Negative Number

There is no root of a negative number since any positive number raised to the second power will result in a positive number.

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\( \sqrt{64}= \)

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Square Root of a Negative Number

Everything you need to know about the root of negative numbers is that... it simply does not exist!
Negative numbers do not have a root, if in an exam you come across an exercise involving the root of a negative number, your answer should be that it has no solution.
Want to understand the logic? Keep reading.


What is the root of a number?

The root is some number, let's suppose one that we will call XX that, in fact, will be positive and that, when multiplied by itself will give us XX.
For example, the root of 100100  will be a positive number that if we multiply it by itself we will obtain 100100 .
That is, 1010.
Instead of saying "multiply it by itself" we can say "raise it to the square".


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Why does a negative number not have a square root?

As we have seen, the root of any number, for example, AA is a positive number that if we square it will give us AA.
There is no positive number in the whole world that when squared will give us a negative number, therefore, negative numbers do not have a root.


Exercise Practice

Solve the exercise:
9=3\sqrt9=3
If we raise 33 to the power of two, we will get 99.
Another exercise
9=No solution\sqrt{-9} = No~solution
We will not be able to find any positive number that, when squared, gives us 9-9 since any positive number squared will be positive and never negative.


Do you know what the answer is?

Examples with solutions for Square Root of a Negative Number

Exercise #1

Choose the largest value

Video Solution

Step-by-Step Solution

Let's begin by calculating the numerical value of each of the roots in the given options:

25=516=49=3 \sqrt{25}=5\\ \sqrt{16}=4\\ \sqrt{9}=3\\ We can determine that:

5>4>3>1 Therefore, the correct answer is option A

Answer

25 \sqrt{25}

Exercise #2

441= \sqrt{441}=

Video Solution

Step-by-Step Solution

The root of 441 is 21.

21×21= 21\times21=

21×20+21= 21\times20+21=

420+21=441 420+21=441

Answer

21 21

Exercise #3

5+361= 5+\sqrt{36}-1=

Video Solution

Step-by-Step Solution

To solve the expression 5+361= 5+\sqrt{36}-1= , we need to follow the order of operations, often remembered by the acronym PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction).


Here are the steps:


First, calculate the square root:

36=6 \sqrt{36} = 6

Substitute the square root back into the expression:

5+61 5 + 6 - 1

Next, perform the addition and subtraction from left to right:

Add 5 and 6:

5+6=11 5 + 6 = 11

Then subtract 1:

111=10 11 - 1 = 10

Finally, you obtain the solution:

10 10

Answer

10 10

Exercise #4

Solve the following exercise:

x2= \sqrt{x^2}=

Video Solution

Step-by-Step Solution

In order to simplify the given expression, we will use two laws of exponents:

a. The definition of root as an exponent:

an=a1n \sqrt[n]{a}=a^{\frac{1}{n}} b. The law of exponents for power of a power:

(am)n=amn (a^m)^n=a^{m\cdot n}

Let's start with converting the square root to an exponent using the law mentioned in a':

x2=(x2)12= \sqrt{x^2}= \\ \downarrow\\ (x^2)^{\frac{1}{2}}= We'll continue using the law of exponents mentioned in b' and perform the exponent operation on the term in parentheses:

(x2)12=x212x1=x (x^2)^{\frac{1}{2}}= \\ x^{2\cdot\frac{1}{2}}\\ x^1=\\ \boxed{x} Therefore, the correct answer is answer a'.

Answer

x x

Exercise #5

81+81+10= 81+\sqrt{81}+10=

Video Solution

Step-by-Step Solution

To solve the expression 81+81+10 81+\sqrt{81}+10 , we need to follow the order of operations, often abbreviated as PEMDAS (Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right)).

Here, the expression contains a square root, which is a type of exponent operation. Therefore, we will handle the square root first:

  • Find the square root of 81, which is calculated as follows: 81=9 \sqrt{81} = 9 .

Now substitute the result back into the original expression:

81+9+10 81 + 9 + 10

Next, perform the addition operations from left to right:

  • First, add 81 and 9: 81+9=90 81 + 9 = 90 .
  • Then, add the result to 10: 90+10=100 90 + 10 = 100 .

Therefore, the final result of the expression 81+81+10 81+\sqrt{81}+10 is:

100 100

Answer

100 100

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