Question

y= x / (x^2+x)

what are the discontinuities on this graph ?

Answer 1

what happens at x=-1

Answer 2

more interesting, what happens when x = 0 ?

y = x/(x(x+1))
= 1/(x+1) , x ≠ 0
http://www.wolframalpha.com/input/?i=plot+y%3D+x+%2F+(x%5E2%2Bx)
so you also have a "hole" at (0,1)

e.g. let x = .0001
y = .0001/(.0001(1.0001))
= appr .99900999...