Math polynomial and zeros help.. Please?

Hi everyone! I'm stuck on a math problem and have no clue how to do it. Can you please show me the steps on how to get the right zeros? Thanks!

For the polynomial, one zeros is given. Find the other zero.

x cubed + x squared + 3x -5 x= -1-2i
Update: Thats it:

For each of the polynomials, one of the zeros is given. Find the other zeros.

x cubed + x squared +3x - 5, x = -1-2i
3 answers 3