Answer
The length of one side of the square is (10r-11)
Work Step by Step
Given the polynomial
$(10r)^{2}$ - 220r + $(11)^{2}$
We see that the polynomial has the first and last term squared and the middle term is -2 times the first and last term. Thus it follows the rule of
$a^{2}$ - 2ab + $b^{2}$ = $(a-b)^{2}$
In this polynomial a= 10r and b=11
$(10r)^{2}$ - 2(10r)(11) + $(11)^{2}$ = $(10r-11)^{2}$
Since the area of a square is $Length^{2}$. The length of one side is the square root of the answer.
$\sqrt (10r-11)^{2}$ = $(10r-11)^{2}$
