Question 1156705
the third root is -2i, since complex numbers come in conjugates
(x+4)=0
x+2i=0
x-2i=0
multiply the second and third together and get x^2-4i^2 or x^2+4
multiply that by (x+4)
x^3+4x^2+4x+16

{{{graph(300,300,-10,10,-100,100,x^3+4x^2+4x+16)}}}