When x³-2x^2-15x is factored completely, one of the factors is x-5.
To factor the expression, we can use the method of grouping. We can rewrite the expression as follows:
x³-2x^2-15x = (x³-2x^2) - 15x
We can then factor the first two terms using the difference of squares:
x³-2x^2-15x = (x-2)(x^2+2x) - 15x
We can then factor the last term using the difference of squares:
x³-2x^2-15x = (x-2)(x^2+2x) - (5)(3x)
Then, we can combine the two factors to get the final answer:
x³-2x^2-15x = (x-5)(x^2+2x-3x)
The final factorization is:
x³-2x^2-15x = (x-5)(x^2-x)
So, the correct answer is (A) x-5.