Question 270279
Hints:


A) Simply plug in {{{x=-3i}}} and show that doing so will result in 0. In other words, show that {{{P(-3i)=0}}}


B) Since -3i is a root, 3i is also a root. This means that {{{x^2+9}}} is a factor. Now use {{{x^2+9}}} to factor {{{x^4-2x^3+7x^2-18x-18 }}} (use polynomial long division) into two quadratics. Factor the resulting quadratic further if possible.