## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$z(z+6)(z^2-6)$
Factoring the $GCF= z$, then the given expression, $z^4+6z^3-6z^2-36z$ is equivalent to \begin{array}{l} z(z^3+6z^2-6z-36) .\end{array} Using factoring by grouping, the factored form of the expression, $z(z^3+6z^2-6z-36) ,$ \begin{array}{l} z[(z^3+6z^2)-(6z+36)] \\\\= z[z^2(z+6)-6(z+6)] \\\\= z[(z+6)(z^2-6)] \\\\= z(z+6)(z^2-6) .\end{array}