Which expression is equal to

Answer:
[tex]6i \sqrt{3}[/tex]
Step-by-step explanation:
To simplify a negative square root, you can rewrite the [tex]\sqrt{-27}[/tex]:
[tex]\sqrt{-27}[/tex] == [tex]\sqrt{-1 * 27}[/tex]
Which can then be rewritten itself as:
[tex]\sqrt{-1} * \sqrt{27}[/tex]
Now, you need to factor the 27, traditionally you will get to remember these but:
[tex]\sqrt{3 * 9} * i == \sqrt{3 * 3^{2} }* i[/tex]
As you are square rooting, the [tex]3^{2}[/tex] can be cancelled and simplified:
[tex]3 \sqrt{3} * i[/tex]
Now, as there is already a 2 before the square root, you can simply multiply the 3i by 2:
[tex](3i * 2) \sqrt{3} = 6i \sqrt{3}[/tex]
Hope this helps!