Answer
The possible dimensions of the rectangle are
$2x-9$ and $3x+8$.
Work Step by Step
Find factors of $ac$ that have a sum of $b$.
Since $ac=-432$ and $b=-11$,
find factors of $-432 $ with a sum of $-11$.
These factors are $16$ and $-27$.
...use the factors to rewrite $bx$.
$6x^{2}-11x-72=6x^{2}+16x-27x-72$
...factor out the GCF out of each pair of terms.
$=2x(3x+8)-9(3x+8)$
...use the Distributive Property.
$=(2x-9)(3x+8)$
The possible dimensions of the rectangle are
$2x-9$ and $3x+8$.
