Solve Quadratic Equations by Completing the Square · Exercise 40

Yvette wants to put a square swimming pool in the corner of her backyard. She will have a 3 foot deck on the south side of the pool and a 9 foot deck on the west side of the pool. She has a total area of 1080 square feet for the pool and two decks. Solve the equation $\left(s+3\right)\left(s+9\right)=1080$ for $s$, the length of a side of the pool.

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Elementary Algebra 2e · §10.2 Solve Quadratic Equations by Completing the Square · Exercise 40