What is the factored form of the function f(x)=x³+2x²-15x-36

  (x+3)(x+3)(x-4)

Step-by-step explanation:

I find a graphing calculator immensely helpful for factoring problems. Of course the constant in the binomial factor is the opposite of the x-intercept value. The x-intercept at -3 just touches the axis, so has even multiplicity. It will give rise to a repeated factor.

The x-intercepts of -3, -3 and +4 mean the factorization is ...

  f(x) = (x +3)(x +3)(x -4)