Answer
(a) See graph, opens up, vertex $(2,-4)$, axis of symmetry $x=2$, intercept(s) $(0,0),(4,0)$.
(b) domain $(-\infty,\infty)$, range $[-4,\infty)$.
(c) increasing on $(2,\infty)$, decreasing on $(-\infty,2)$.
Work Step by Step
(a) See graph for $y=x^2-4x=(x-2)^2-4$, we can find that the graph opens up, vertex $(2,-4)$, axis of symmetry $x=2$, y-intercept $(0,0)$, x-intercept(s) $(0,0),(4,0)$.
(b) We can determine the domain $(-\infty,\infty)$, range $[-4,\infty)$.
(c) The function is increasing on $(2,\infty)$, decreasing on $(-\infty,2)$.
