Question 1126680
Possible zeros may be  -1, 1, -1/3, 1/3, -2/3, 2/3, -2, 2.


Expect up to four zeros, because degree is four.


Try synthetic division and you will find zeros of -1, and 1/3.
Factor still to check is {{{3x^2-6x+6}}}
which using solution for quadratic equation shows zeros of 1-i and 1+i.



{{{system(the_zeros,-1,1/3,1-i,1+i)}}}