Answer
$(y+9)^2$
Work Step by Step
The first term in each binomial must be y, since $y^2$ has no coefficient.
The operation in each binomial must be addition, since each term in the trinomial is positive.
$9+9=18$ and $9\times9=81$, so the other two terms are 9 and 9.
Since the two binomials contain the same expression they are written with an exponent of 2,
