Answer
$(y-11)^2$
Work Step by Step
The expression above is equivalent to
\begin{array}{l}\require{cancel}
y^2+121-22y
\\\\=
y^2-22y+121
.\end{array}
Using the factoring of trinomials in the form $x^2+bx+c,$ the $\text{
expression
}$
\begin{array}{l}\require{cancel}
y^2-22y+121
\end{array} has $c=
121
$ and $b=
-22
.$
The two numbers with a product of $c$ and a sum of $b$ are $\left\{
-11,-11
\right\}.$ Using these two numbers, the $\text{
expression
}$ above is equivalent to
\begin{array}{l}\require{cancel}
(y-11)(y-11)
\\\\=
(y-11)^2
.\end{array}
