Answer
a.
x-intercepts: $0$ and $4$
y-intercept: $0$.
b.
($3,\ -3$) is a local minimum.
Work Step by Step
a.
The graph intersects the x-axis at ($0$,0) and ($4$,0)
(x-intercepts: $0$ and $4$)
The graph intersects the y-axis at (0,$0$).
(y-intercept: $0$)
b.
Local maxima/minima are found when there exists a rectangle
for which there is one point with greatest/least function values (within that rectangle).
($3,\ -3$) is a local minimum,
(surrounding points have greater function values).
There are no local maxima.