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

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Answer 1 · 2016-06-13T20:11:54

$(z + 2)(z + 4)(z - 4)$

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

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

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

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