Problem: Which one of the following points is not on the graph of y=x+1x​?
Answer Choices:
A. (0,0)
B. (−21​,−1)
C. (21​,31​)
D. (−1,1)
E. (−2,2)
Solution:
Since x+1x​ is not defined when the denominator is zero, and since the denominator x+1 equals zero when x=−1, any point whose abscissa is −1 , such as (−1,1) can not be on the graph.