Question 634547
<pre>
The graph of xy = 0 by the 0 factor principle is equivalent

to the combined graphs of x = 0 and y = 0.  These are the two axes.

So the graph is all the points on the x or y-axes.

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The graph of xy = -1 is the graph of y = {{{-1/x}}}, which is
this hyperbola:

{{{graph(400,400,-6,6,-6,6,-1/x)}}}

All the points on this graph are in the 2nd and 4th quadrants.

Edwin</pre>