Answer:
4i
Step-by-step explanation:
I hope its not too complicated
[tex]\sqrt{-16} \\\\\mathrm{Apply\:radical\:rule}:\quad \sqrt{-a}=\sqrt{-1}\sqrt{a}\\\\\sqrt{-16}=\sqrt{-1}\sqrt{16}\\\\\mathrm{Apply\:imaginary\:number\:rule}:\quad \sqrt{-1}=i\\\\=\sqrt{16}i\\\\\sqrt{16}=4\\\\=4i[/tex]
