There are three real numbers $x$ that are not in the domain of$$f(x) = \frac{1}{1+\frac{1}{1+\frac 1x}}.$$What is the sum of those three numbers?
+876 X = 0
1+1/x=0
x+1=0
x=-1
1+1/(1+1/x) = 0
1 + 1/x + 1 = 0
2+ 1/x = 0
2x +1 = 0
2x = -1
x = -1/2
0+(-1)+(-1/2)=-3/2
