Question 1099067
the other zero is 1-i,since they are conjugate.
one factor is (x+4)
Using the quadratic formula, one wants to end up with  [2+/- sqrt (-4)]/2, because that will reduce to 1+/-i

Therefore, using the quadratic formula, b=-2 and (b^2-4ac) must be -4, because the square root of -4 is +/-2i, and 2i/2=1, assuming a=1, which is the easiest case for Ax^2+Bx+C
That would be 4-4ac=-4 and a=1
so 4-4c=-4
-4c=-8
c=2
the quadratic factor is x^2-2x+2
The polynomial is the product of the two factors
x^3+4x^2-2x^2-8x+2x+8
x^3+2x^2-6x+8
{{{graph(300,300,-10,10,-10,30,x^3+2x^2-6x+8)}}}