The large Square above has area 9 is divided into 9 smaller squares of equal area what is the length of how strong and bold

If one square is divided into 9 smaller equal squares, then they have to be arranged in 3 lines of 3, that is 3 smaller equal squares per side of the original big square. That said, the area of the big square is equal to the multiplication of 3 small squares sides times 3 small squares sides, call x the length of the small squares.

So,

area = 9 = 3x*3x

9x^2 = 9

x^2 = 1

x = 1

therefore the smaller squares have sides of 1 unit