You need to remember what is the formula of the volume of the cube:
V = Area of the base*height.
Since all the faces of the cube are equal squares, the length of the height is equal to the length of the square base.
Let the length of the side of the square be "l".
`A = l^2`
`` `V = l^2*l = l^3`
If the length of the side of the cube is `l = (x+2)^3 =gt l^3 = [(x+2)^3]^3 =gt l^3 = (x+2)^9` .
The volume of the cube whose length of the side is `(x+2)^3` is`V = (x+2)^9` .