Question 1059324
Possible roots to check are  -28, -14, -7, -1, -2, 1, 2, 7, 14, 28.


Each time a root is found  (remainder in synthetic division is 0), fewer roots need to be checked.  Refer to Rational Roots Theorem and Factor Theorem.  Try the smaller sized roots first.  Begin checking for 2 as a root.  The resulting quadratic factor will probably have complex non-real roots.