Question 972920
-3 and 1+5i ARE ZEROS.
This must also include 1-5i.  


Start with {{{f(x)=k(x+3)(x-(1+5i))(x-(1-5i))}}}, and simplify into general form, but keep the unknown factor k, UNDISTRIBUTED.


Next step from the raw factored form,
{{{k(x+3)((x-1)-5i)((x-1)+5i)}}}
and then
{{{k(x+3)((x-1)^2-(5i)^2)}}}
Keep going...