Answer:
[tex]\large\boxed{3\sqrt{16}+\sqrt{-9}=12+3i}[/tex]
Step-by-step explanation:
[tex]3\sqrt{16}+\sqrt{-9}\\\\\sqrt{16}=4\ \text{because}\ 4^2=16\\\\\sqrt{-9}=\sqrt{(9)(-1)}\qquad\text{use}\ \sqrt{ab}=\sqrt{a}\cdot\sqrt{b}\\=\sqrt9\cdot\sqrt{-1}=(**)\\\sqrt9=3\ \text{because}\ 3^2=9\\\sqrt{-1}=i\\(**)=3i\\\\3\sqrt{16}+\sqrt{-9}=(3)(4)+3i=12+3i[/tex]
