Question 762784
Your THREE roots are -1, -2+3i, AND -2-3i.


Build your polynomial function using the polynomial factors according to the now known roots:


{{{highlight((x+1)(x-(2-3i))(x-(2+3i)))}}}
Let us do something more convenient with the complex polynom factors.
{{{(x+1)(x-2+3i)(x-2-3i)}}}
{{{(x+1)((x-2)+3i)((x-2)-3i)}}}
You should notice what makes the difference  of two squares.
{{{(x+1)((x-2)^2 - (3i)^2)}}}
{{{(x+1)(x^2-4x+4+9)}}}
{{{highlight((x+1)(x^2-4x+13))}}}