ANSWER
n=5
EXPLANATION
The area of a square is given by
[tex] {l}^{2} [/tex]
where l is the length of the sides.
If the area is
[tex] {x}^{10} [/tex]
then we can rewrite this as
[tex]( { {x}^{5}) }^{2} [/tex]
This implies that:
[tex] {l}^{2} = ( { {x}^{5}) }^{2} [/tex]
Hence,
[tex]l = {x}^{5}[/tex]
Therefore n=5