Respuesta :

ghaithgh

Answer:

The choice 4 and 6 ;

[tex]7i(7i)[/tex]

and

[tex](9 + 3i)(9 - 3i)[/tex]

Step-by-step explanation:

[tex]7i(7i) = 49 {i}^{2} = - 49[/tex]

__o_o__

[tex](9 + 3i)(9 - 3i) \\ = 81 - 27i + 27i - 9 {i}^{2} \\ = 81 + 9 \\ = 90[/tex]