Answer:
-4
Step-by-step explanation:
Ok first we can factor out 3x and get
[tex]f(x)=3(x^3+4x^2+x+6)[/tex]
then factor it
[tex]f(x)=3(x^2(x-1)+5x(x-1)+6(x-1))\\f(x) = 3(x-1)(x^2+5x+6)\\f(x) = 3(x-1)(x+3)(x+2)\\x = 1, -3, -2[/tex]
add em together, we get -4
