Answer:
(x^2 - 16)(x - 4)
Explanation:
Split the whole expression in half, and take out the common factors. So let's first work on x^3 - 4x^2. So a common factor that they both have is x^2, so you would take that out; x^2 (x - 4), and a common factor that -16x + 64 is -16. If you take that out, it would look like this, -16(x - 4). Since there's two (x - 4), you just keep one and you combine the x^2 and -16. And then you just put it all together, (x^2 - 16)(x - 4).