Answer:
The length of a side of the original square is 6 meters
Step-by-step explanation:
Let
x ----> the length side of the original square
The area of a square is equal to
[tex]A=b^2[/tex]
where
b is the length side of the square
In this problem
The new length side of the square is [tex]b=(x+3)\ m[/tex] and the area is [tex]A=81\ m^2[/tex]
so
[tex](x+3)^2=81[/tex]
solve for x
take square root both sides
[tex](x+3)=9[/tex]
[tex]x=9-3=6\ m[/tex]
