Answer
$(x-4)(x+3)(x-3)$
Work Step by Step
The product of a binomial sum and a binomial difference is: $(A+B)(A-B)=A^2-B^2$.
The square of a binomial sum is: $(A+B)^2=A^2+2AB+B^2$.
The square of a binomial difference is: $(A-B)^2=A^2-2AB+B^2$.
Hence here: $x^3-4x^2-9x+36=\\=x^2(x-4)-9(x-4)\\=(x-4)(x^2-9)\\=(x-4)(x^2-3^2)\\=(x-4)(x+3)(x-3)$