## Precalculus (6th Edition)

$\color{blue}{36r^2-60r+25}$
Use the formula $(a-b)^2=a^2-2ab+b^2$ with $a=6r$ and $b=5$ to obtain: $=(6r)^2-2(6r)(5)+5^2 \\=\color{blue}{36r^2-60r+25}$