Answer
$$x^5-6x^4+8x^3-48x^2-9x+54$$
Work Step by Step
Using the factors to find the original polynomial, we obtain:
$$\left(x^2-1\right)\left(x-6\right)\left(x^2+9\right) \\ \left(x^3-6x^2-x+6\right)\left(x^2+9\right) \\ x^5-6x^4+8x^3-48x^2-9x+54$$