The easy factors are 3 and x3-x+9.
x3-x+9 factorises further into one real factor and two complex factors. When x=-2 the cubic has value -8+2+9=3. When x=-3 the value is -27+3+9=-15. So there must be a zero between x=-3 and x=-2. At first guess we can average these two values of x: -2.5. If we now find the value of the cubic for x=-2.5 we get -15.625+2.5+9=-4.125, so, since this is negative and the value of the cubic was 3 when x=-2, the zero must be between x=-2 and -2.5. The average of these two values of x is -2.25. If we continue this process we eventually get to x=-2.24 (approx). When this value is substituted into the cubic, its value becomes 0.000576, which is quite close to zero, showing that x=-2.24 is an approximate root or zero of the cubic x3-x+9. This makes x+2.24 an approximate factor. we can use a form of synthetic division to reduce the cubic to a quadratic:
-2.24 | 1 0 -1 | 9
1 -2.24 5.02 | -9
1 -2.24 4.02 | 0 = x2-2.24x+4.02 (approximately).
x=(2.24±√(2.242-4×4.02))/2=1.12±1.66i (approx), where i=√-1 (imaginary).
So the two other factors are x-1.12+1.66i and x-1.12-1.66i.