Answer:
C
Step-by-step explanation:
We want to simplify the expression:
[tex]\displaystyle 3 \sqrt{-28}[/tex]
Rewrite:
[tex]\displaystyle = 3 \sqrt{ 4\cdot 7 \cdot -1}[/tex]
Rewrite:
[tex]\displaystyle = 3 \cdot \sqrt{4} \cdot \sqrt{7} \cdot \sqrt{-1}[/tex]
Simplify. Let i = √(-1). Hence:
[tex]\displaystyle = 3 \cdot \left(2\right) \cdot \left(i\right) \cdot \sqrt{7}[/tex]
Multiply:
[tex]\displaystyle = 6i\sqrt{7}[/tex]
In conclusion, our answer is C.