Step-by-step explanation:
Our roots are 3, and i so our roots form
will be
[tex](x - 3)(x - i)[/tex]
Since i is one root, it conjugate, must be the other.
so we have
[tex](x - 3)(x - i)(x + i)[/tex]
Simplify
[tex]( {x}^{2} + 1)(x - 3)[/tex]
[tex] {x}^{3} - 3 {x}^{2} + x - 3[/tex]
So the function is
[tex]x {}^{3} - 3 {x}^{2} + x - 3[/tex]