>>100551644this is a graph for 1/x
if you approach 0 from the negative side, you go to negative infinity. If you approach from the positive side, you go to positive infinity.
So what is it at 0?? It's unclear, nobody knows.
Also algebra just "breaks" when you can divide by zero. It no longer gives you the right answers.
Probably the simplest example
0 = 0
1*0 = 2*0
1 = 2
doesn't work, breaks everything