Question 937897
Maybe this misses some fundamental skills, but maybe try some software, or a program of you own design to apply synthetic division to look for roots, or to test each possible root  (to see if the remainder is 0).  Rational Roots theorem will help you find several roots to check, and then synthetic division should tell you if the root is part of the function f(x).  On paper, the division process can become messy.  That's why I suggest some kind of software.  


You might also try a graphing tool to indicate rational roots, which can tell you directly the binomial factors of f(x).


Using the graphing feature of Google.com, two roots are at -2 and 3.  Another couple roots occur between them; one seems to be 0.5, and then,.... 
by that extent, you would more easily be able to analyze the simpler factor remaining after the three synthetic divisions.