Question

How do you factor `z^3 + 2z^2 - 16z - 32` by grouping?

Answer 1

`(z + 2)(z + 4)(z - 4)`

Explanation:

There are 4 terms, so group them into two group of two - make sure there is a PLUS sign between the groups.

`(z^3 + 2z^2) + (-16z -32) " common factor from each pair"`
=`z^2(z + 2) -16(z + 2)" note -16 as the common factor"`
=`(z+2)(z^2 - 16)`

=`(z + 2)(z + 4)(z - 4)`