Answer: (x +4)(x - 4)
Step-by-step explanation: Since x² - 16 represents the difference of two squares, it can be factored as the product of two binomials, one that has a plus in it and one that has a minus in it.
The first position in each binomial is filled by
the factors of x² that are the same, x times x.
The second position in each binomial is filled
by the factors of 16 that are the same, 4 times 4.
The answer therefore is (x + 4)(x - 4).