## Precalculus (6th Edition)

$\color{blue}{z(-9z^2+7z+1)}$
Each term has the variable $z$. The lowest exponent of $x$ is $1$. Thus, the GCF is $z^1$ or $z$. Factor out $z$ to obtain: $=z(7z-9z^2+1) \\=\color{blue}{z(-9z^2+7z+1)}$