Find all integer roots of f(x). Identify any double roots.
f(x) = 3x4 - 16x3 + 31x2 - 26x + 8
try x = 1
yes that works so divide by (x-1)
(x-1)(3x^3-13x^2+18x-8)
try x=1 again
yes that works so divide by (x-1)again
(x-1)(x-1)(3x^2-10x+8)
factor that quadratic
(x-1)(x-1)(3x-4)(x-2)
so
x = 1, 1 , 2, 4/3