Answer
(a) See graph, opens down, vertex $(2,4)$, axis of symmetry $x=2$, intercept(s) $(0,0),(4,0)$.
(b) domain $(-\infty,\infty)$, range $(-\infty,4]$.
(c) decreasing on $(2,\infty)$, increasing 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 down, 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 $(-\infty,4]$.
(c) The function is decreasing on $(2,\infty)$, increasing on $(-\infty,2)$.
