Why Does the Square Root of a Squared Algebraic Term Equal the Term Itself?

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In summary, the conversation discusses the relationship between square roots and algebraic terms, particularly how the radicand (the number under the square root sign) is equal to the term itself if the term is non-negative. It also touches on the concept of absolute value and its connection to square roots.
  • #1
mathdad
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Let A be an a algebraic term.

Why does the sqrt{(A)^2} = A?

In other words, why does the radicand simply come out of the square root?
 
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  • #2
That only works if $A$ is non-negative. More precisely, there is the definition:

\(\displaystyle |A|\equiv\sqrt{A^2}\)

Let's now assume that $0\le A$. Then we can think of this along these lines:

\(\displaystyle \sqrt{A^2}=\left(A^2\right)^{\frac{1}{2}}=A^{2\cdot\frac{1}{2}}=A^1=A\)
 
  • #3
MarkFL said:
That only works if $A$ is non-negative. More precisely, there is the definition:

\(\displaystyle |A|\equiv\sqrt{A^2}\)

Let's now assume that $0\le A$. Then we can think of this along these lines:

\(\displaystyle \sqrt{A^2}=\left(A^2\right)^{\frac{1}{2}}=A^{2\cdot\frac{1}{2}}=A^1=A\)

Are you saying that sqrt{(-A)^2} does not equal A?
 
  • #4
RTCNTC said:
Let A be an a algebraic term.

Why does the sqrt{(A)^2} = A?
It doesn't. If A= -2 then A^2= 4 and sqrt(4)= 2 not -2.

In other words, why does the radicand simply come out of the square root?
 
  • #5
What about sqrt{(x^2 + 1)^2}?

The square root of a quantity squared is the quantity itself.

Does that equal x^2 + 1?
 
  • #6
Yes, but only because $x^2+1=|x^2+1|$, as $x^2+1$ is always positive.
 
  • #7
greg1313 said:
Yes, but only because $x^2+1=|x^2+1|$, as $x^2+1$ is always positive.

Only because |x^2 + 1| is always positive. Is this what you're saying?
 
  • #8
Are you familiar with absolute value?
 
  • #9
greg1313 said:
Are you familiar with absolute value?

I am familiar with the basic idea of absolute value. However, in what way is absolute value connected to square roots, particularly my question here?
 
  • #10
See Mark's post in this topic, http://mathhelpboards.com/pre-calculus-21/sqrt-something-2-a-22221-post100174.html#post100174. (Post #2)
 
  • #11
I guess I have a lot more to learn.
 

FAQ: Why Does the Square Root of a Squared Algebraic Term Equal the Term Itself?

What is the meaning of "Sqrt{(something)^2}"?

"Sqrt" stands for square root and "(something)^2" represents a number or expression raised to the power of 2. Therefore, "Sqrt{(something)^2}" means the square root of a number or expression squared.

How do you solve for the value of "Sqrt{(something)^2}"?

To solve for the value of "Sqrt{(something)^2}", you first need to find the square root of the number or expression inside the parentheses. Then, square the result to get the final answer. For example, if "something" is 4, then "Sqrt{(something)^2}" would be equal to 4.

What is the relationship between "Sqrt{(something)^2}" and absolute value?

The expression "Sqrt{(something)^2}" and absolute value are closely related. The square root of a number squared will always result in the absolute value of that number. In other words, "Sqrt{(something)^2}" is another way of expressing the absolute value of "something".

Can "Sqrt{(something)^2}" be negative?

No, the square root of any number squared will always be positive. This is because squaring a negative number will result in a positive number, and taking the square root of a positive number will also result in a positive number.

How is "Sqrt{(something)^2}" used in real life?

The square root of a number squared is commonly used in various mathematical and scientific calculations, such as finding the distance between two points on a coordinate plane or calculating the magnitude of a vector. It is also used to solve equations involving quadratic functions and to find the length of the hypotenuse in a right triangle.

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