This is the sum of two cubes. We have x^3 which is x cubed and 64 which is 4 cubed.
The base formula is:
(a+b)(a^2+ab+b^2)
In case case a = x and b = 4.
There is a similar case where you are finding the difference between two cubes. The formula for it is:
(a-b)(a^2+ab+b^2)