a) As you can notice, the parabola open downward, because there is a maximum.
b) The equation of the axis of symmetry is given by the x-coordinate of the vertex. You can see in the graph that the vertex of the parabola (also the maximum point in this case) is (4,2). Then, the equation of the axis of symmetry is:
x = 4
c) The vertex is (4,2)
d) Consider that the x-intercepts are the x-coordinates at which the curve crosses the x-axis. Based on the graph you can see that x-intercepts are
x = 2
x = 6
Y-intercept is the y-coordinate of the point at which the curve crosses the
y-axis, in this case, the y-intercept is:
y = -6