The area of the square is obtained by taking the square of the length of one side. Since it is said that the area of the square is less than 100 m^2, taking the square root of that where: sqrt (100) = 10, the side of that square should be less than 10 as well. Among the choices, D. 0 <y <10 (where y = length of side of square) is the correct answer.
What we know:
(Also, 
)
What we need to solve:
(This is equal to 
)
How you have to subtract 
with 
to get:
Thus, the answer would be:
