Question 911048
You can identify the zeros just by inspection.  Test within each interval of the x-axis for sign within the intervals to know if y is positive or negative; and to help identify if y touches the x-axis.


You must do the work; but the graph should look like this:


(THIS GRAPH WILL NOT WORK.  I WILL KEEP TRYING TO STRAIGHTEN THIS...)

{{{graph(300,300,-10,10,-6,15,-x(x+5)(x+3))}}}

Graph is still not working. 
Try this:  visit www.google.com, put y=-x(x+5)(x+3) into the search field, click the GO button, and you should be shown an interactive graph.