Answer
$a.\quad \mathbb{R}$
$b.\quad (0,4)$
$c.\quad $see image
$d.\quad \mathbb{R}\backslash\{0\}=(-\infty,0)\cup(0,\infty)$
$e.\quad $Not continuous (jump at x=0)
Work Step by Step
It's best to graph the function first.
The graph is the line $y=3x$,
with the point (0,0) excluded, and replaced with ($0,4$).
(There is a jump at x=0)
Domain: whole set $\mathbb{R}$
Range : $\mathbb{R}\backslash\{0\}=(-\infty,0)\cup(0,\infty)$
There is no x-intercept.
The y intercept is at ($0,4$)
