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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]


Sagot :

To determine which expression is equivalent to [tex]\(\sqrt{-80}\)[/tex], let's break it down step by step:

1. Understand the complex number property:
The square root of a negative number involves an imaginary unit [tex]\(i\)[/tex], where [tex]\(i = \sqrt{-1}\)[/tex].

2. Express [tex]\(\sqrt{-80}\)[/tex] using the imaginary unit:
We know that [tex]\(\sqrt{-80}\)[/tex] can be written as:
[tex]\[ \sqrt{-80} = \sqrt{-1 \times 80} = \sqrt{-1} \times \sqrt{80} \][/tex]
Since [tex]\(\sqrt{-1} = i\)[/tex], we can write:
[tex]\[ \sqrt{-80} = i \times \sqrt{80} \][/tex]

3. Simplify [tex]\(\sqrt{80}\)[/tex]:
To simplify [tex]\(\sqrt{80}\)[/tex], we factorize 80 into its prime factors:
[tex]\[ 80 = 16 \times 5 \][/tex]
Therefore, we can write:
[tex]\[ \sqrt{80} = \sqrt{16 \times 5} \][/tex]
Using the property of square roots, [tex]\(\sqrt{ab} = \sqrt{a} \times \sqrt{b}\)[/tex], we get:
[tex]\[ \sqrt{80} = \sqrt{16} \times \sqrt{5} \][/tex]
Since [tex]\(\sqrt{16} = 4\)[/tex], this becomes:
[tex]\[ \sqrt{80} = 4 \times \sqrt{5} \][/tex]

4. Combine the results:
Putting it all together, we have:
[tex]\[ \sqrt{-80} = i \times \sqrt{80} = i \times (4 \times \sqrt{5}) = 4i \times \sqrt{5} \][/tex]

Therefore, the expression that is equivalent to [tex]\(\sqrt{-80}\)[/tex] is:
[tex]\[ \boxed{4i \sqrt{5}} \][/tex]