Question 1064761
THESE two factors give a quadratic factor:
{{{(x-(2-6i))(x-(2+6i))}}}
{{{(x-2)^2-36i}}}
{{{highlight_green(x^2-4x+40)}}}.


If you peform long polynomial division  (not shown) for {{{x^4-4x^3+41x^2-4x+40}}} divided by {{{x^2-4x+40}}}, result will be  {{{x^2+1}}}.


{{{f(x)=(x^2-4x+40)(x^2+1)}}}


The two other zeros are  {{{system(-i,and,i)}}}.