Respuesta :

Answer:

Solving the radical [tex]\pm\sqrt{-81}[/tex]  we get [tex]\mathbf{\pm9 \ i}[/tex]

Step-by-step explanation:

We need to express the radical [tex]\pm\sqrt{-81}[/tex] using the imaginary unit i

Prime factors of 81 are: 3x3x3x3

and [tex]\sqrt{-1}=i[/tex]

Solving:

[tex]\pm\sqrt{-81}\\=\pm\sqrt{81}\sqrt{-1}\\=\pm\sqrt{3\times3\times3\times3}i\\ =\pm\sqrt{3^2\times3^2}i\\=\pm3\times3\ i\\=\pm9 \ i[/tex]

So, Solving the radical [tex]\pm\sqrt{-81}[/tex]  we get [tex]\mathbf{\pm9 \ i}[/tex]