Answer
$x^2-4x-96$
Work Step by Step
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the Distributive Property, the given expression, $
(x-12)(x+8)
,$ is equivalent to
\begin{array}{l}\require{cancel}
x(x)+x(8)-12(x)-12(8)
\\\\=
x^2+8x-12x-96
\\\\=
x^2-4x-96
.\end{array}