how to factor 3x^3+7x^2+3x+1

if you let f(x) = 3x^3+7x^2+3x+1

and if we want factors with rational coefficients, the the only choices for
f(x) = 0 would be if x = ±1 or x = ± 1/3

A quick mental check would show that none of these work, so I conclude that there are no rational factors.