Answer
$a.\quad $see image below
$b.\quad (-\infty,\infty)$
$c.\quad $Decreases on$ (-1,2)$
Increases on $( -\infty,-1)\cup(2,\infty)$
Work Step by Step
$a.$
We graph the function using an online graphic calculator.
$b.$
$f$ is defined for all reals, $(-\infty,\infty)$
$c.$
Decreases on$ (-1,2)$
Increases on $( -\infty,-1)\cup(2,\infty)$