Answer:
(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)
