Question

write quadratic equation in standard form with 3i and -3i as its roots

Answer 1

\[(x-3i)(x+3i)\] multiply out

Answer 2

either that, or figure that if the roots are \(\pm3i\) then you must have had \[x^2=-9\] so the equation would be \[x^2+9=0\] and the quadratic is \(x^2+9\)