We'll consider the degree of the function f(x) as being n.
If we'll multiply 2 polynomials, the exponents of matching variables are adding.
If the grade of f(x) is n, then the grade of f'(x) is (n-1) and the grade of f"(x) is (n-2) => n= n-1+n-2 => n=3
Therefore the order of the function f(x) is n=3.
f(x)= ax^3 + bx^2 +cx+d
ax^3 + bx^2 +cx+d=(3ax^2+2bx+c)(6ax+2b)
Comparing, we'll get:
b=18*(1/18)*b, therefore b may be any real number
c=4b^2+6ac => c=6b^2
d=2bc => d=12b^3
The requested function f(x) is f(x)= (1/18)x^3 + bx^2 +6bx+12b^3.