You can put this solution on YOUR website! First thing you do ake yourself if there is a GCF, and since x is in all 3 terms, x is the GCF. So taking the GCF out gives us x(21x^2-62+16). Now you have to factor the trinomial into 2 binomials.
Answer: x(7x-2)(3x-8)
You can disribute to check