Answer:
what are the options? I'll say it in the comments
It has to do with the number of dimensions you have in the figure. For example, in a square you have 2 dimensions, length and width. Since you have only two you use units^2. In a cube, you have 3 dimensions, length, width and height, which is where you get the units^3.
Answer: a = 8
Step-by-step explanation:
Volume of a square based pyramid is given as
.
where a is the length of the side and h is the height.
Substituting into the formula , we have
V = 
128 =
/3
384=
X 6
Divide through by 6
384/6 = 
64 = 
Therefore :
a = 
a = 8