Answer: The required length of a side of the square is (x - 6) units.
Step-by-step explanation: Given that the area of a square is as follows :
We are to find the length of a side of the square.
We know that
all the sides of a square have equal length l, and its area is given by
From expression (i), we have
Therefore, the required length of a side of the square is (x - 6) units.