It's an ! the area of a square can be found using the equation a = s², where a is the area and s is the measure of one side of the square. match the equation for how to solve for the side length of a square to its description.

The answer is the first tile on the very left
s = sqrt(227) where "sqrt" is shorthand for "square root"

To get this answer, we basically replace A with 227 and we go from
A = s^2
to
227 = s^2

So if s^2 = 227, then s = sqrt(227) after we apply the square root to both sides. Because s is some length value, it makes no sense to have it negative. Therefore we don't consider the negative version of the square root.