Which expression is equivalent to [tex]$\sqrt{-80}$[/tex]?

A. [tex]-4 \sqrt{5}[/tex]
B. [tex]-4 i \sqrt{5}[/tex]
C. [tex]4 i \sqrt{5}[/tex]
D. [tex]4 \sqrt{5}[/tex]



Answer :

To determine which expression is equivalent to [tex]\(\sqrt{-80}\)[/tex], let's analyze the value step by step.

Firstly, recall that we can rewrite [tex]\(\sqrt{-80}\)[/tex] as:

[tex]\[ \sqrt{-80} = \sqrt{-1 \cdot 80} \][/tex]

We know that [tex]\(\sqrt{-1}\)[/tex] is denoted as [tex]\(i\)[/tex], where [tex]\(i\)[/tex] is the imaginary unit. Therefore, the expression becomes:

[tex]\[ \sqrt{-80} = \sqrt{80} \cdot i \][/tex]

Next, simplify [tex]\(\sqrt{80}\)[/tex]:

[tex]\[ \sqrt{80} = \sqrt{16 \cdot 5} = \sqrt{16} \cdot \sqrt{5} \][/tex]

Since [tex]\(\sqrt{16} = 4\)[/tex], we get:

[tex]\[ \sqrt{80} = 4 \cdot \sqrt{5} \][/tex]

Now substitute this back into the expression for [tex]\(\sqrt{-80}\)[/tex]:

[tex]\[ \sqrt{-80} = 4 \cdot \sqrt{5} \cdot i = 4i \cdot \sqrt{5} \][/tex]

Having found that [tex]\(\sqrt{-80} = 4i \sqrt{5}\)[/tex], we can match this with the given choices:

[tex]\[ -4 \sqrt{5} \][/tex]

[tex]\[ -4 i \sqrt{5} \][/tex]

[tex]\[ 4i \sqrt{5} \][/tex]

[tex]\[ 4 \sqrt{5} \][/tex]

Clearly, the expression 4i [tex]\(\sqrt{5}\)[/tex] matches our derived equivalent expression for [tex]\(\sqrt{-80}\)[/tex].

Therefore, the correct answer is:

4i [tex]\(\sqrt{5}\)[/tex]