Let's start by plotting the three points through which we know the function passes. It crosses the x-axis at two places, x=-4 and x=4. Also, its y-intercept is y=16.
We are also told that the graph has relative maximum at the y-intercept. Additionally, it is increasing for x<0 and decreasing for x>0. Now, we have enough information to graph the function.
Note, our graph is one of many possible solutions.