That is an unusual graph :)
That's because it is actually two graphs: y = -1 + 1/x and y = 1
The question that I am now asking myself is how do I determine the ends of the hole around a=1 the graphs indicate that it is more than just one point ????
It's just a plotting oddity (possibly arising because of plotting two functions as though they are 1?). Plot y=-1+1/x on the same graph and you will see it overwrites the curve without a large hole around x = 1.
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