What is the sum of [tex]\sqrt{-2}[/tex] and [tex]\sqrt{-18}[/tex]?

A. [tex]4 \sqrt{2}[/tex]
B. [tex]4 i \sqrt{2}[/tex]
C. [tex]5 \sqrt{2}[/tex]
D. [tex]5 i \sqrt{2}[/tex]



Answer :

To find the sum of [tex]\(\sqrt{-2}\)[/tex] and [tex]\(\sqrt{-18}\)[/tex], we need to first express these square roots in terms of imaginary numbers.

1. Calculate [tex]\(\sqrt{-2}\)[/tex]:
[tex]\[ \sqrt{-2} = \sqrt{2 \cdot -1} = \sqrt{2} \cdot \sqrt{-1} = \sqrt{2} \cdot i = i \sqrt{2} \][/tex]

2. Calculate [tex]\(\sqrt{-18}\)[/tex]:
[tex]\[ \sqrt{-18} = \sqrt{18 \cdot -1} = \sqrt{18} \cdot \sqrt{-1} = \sqrt{18} \cdot i \][/tex]
Next, simplify [tex]\(\sqrt{18}\)[/tex]:
[tex]\[ \sqrt{18} = \sqrt{9 \cdot 2} = \sqrt{9} \cdot \sqrt{2} = 3 \cdot \sqrt{2} = 3\sqrt{2} \][/tex]
Thus,
[tex]\[ \sqrt{-18} = 3\sqrt{2} \cdot i = 3i \sqrt{2} \][/tex]

3. Sum up [tex]\(\sqrt{-2}\)[/tex] and [tex]\(\sqrt{-18}\)[/tex]:

Add [tex]\(i \sqrt{2}\)[/tex] and [tex]\(3i \sqrt{2}\)[/tex]:
[tex]\[ i \sqrt{2} + 3i \sqrt{2} = (1i \sqrt{2} + 3i \sqrt{2}) = 4i \sqrt{2} \][/tex]

Therefore, the sum of [tex]\(\sqrt{-2}\)[/tex] and [tex]\(\sqrt{-18}\)[/tex] is:

[tex]\[ 4i \sqrt{2} \][/tex]

So the correct answer is:
[tex]\[ \boxed{4 i \sqrt{2}} \][/tex]