Chapter R - Review Exercises - Page 75: 64

$z \left( -9z^2+7z+1 \right)$

Factoring the $GCF= z ,$ then the given expression, $ 7z^2-9z^3+z ,$ is equivalent to \begin{array}{l}\require{cancel} z \left( \dfrac{7z^2}{z}-\dfrac{9z^3}{z}+\dfrac{z}{z} \right) \\\\= z \left( 7z-9z^2+1 \right) \\\\= z \left( -9z^2+7z+1 \right) .\end{array}