Question
Which of the following relation is NOT a function ?
A.
$$f = \left\{ {\left( {x,\,x} \right)|x\, \in \,R} \right\}$$
B.
$$g = \left\{ {\left( {x,\,3} \right)|x\, \in \,R} \right\}$$
C.
$$h = \left\{ {\left( {n,\,\frac{1}{n}} \right)|n\, \in \,I} \right\}$$
D.
$$t = \left\{ {\left( {n,\,{n^2}} \right)|n\, \in \,N} \right\}$$
Answer :
$$h = \left\{ {\left( {n,\,\frac{1}{n}} \right)|n\, \in \,I} \right\}$$
Solution :
If $$n = 0$$ then $$h\left( n \right)$$ is not defined, so, $$'h'$$ is not a function. All other are functions.