What is the completely factored form of x3 – 64x?
x(x – 8)(x – 8)
(x-4){x^2+4x+16}
x(x – 8)(x + 8)
(x – 4)(x + 4)(x + 4)

The answer is x(x-8)(x+8)
Here is the process;
x^3-64x
x(x^2-64)
You know that it will be a x- and a x+ becuase there is no middle x value
x(x-)(x+)
x(x-8)(x+8)

Remember difference of 2 perfect squares
a²-b²=(a-b)(a+b)

first factor out x

x(x²-64)
x(x²-8²)
x(x-8)(x+8)

answer is 3rd option