Answer:
[tex]729a^6\ ft^2[/tex]
Step-by-step explanation:
The area of the square is
[tex]A_{square}=\text{Side}^2[/tex]
If one side of the plot was [tex](3a)^3[/tex] feet long, then the area of the square plot is
[tex]A_{Square\ plot}=((3a)^3)^2\ ft^2[/tex]
Simplify this expression
[tex]A_{Square\ plot}=((3a)^3)^2=(3a)^3\cdot (3a)^3=27a^3\cdot 27a^3=27\cdot 27\ccdot a^{3+3}=729a^6\ ft^2[/tex]