Step-by-step explanation:
Look at the picture.
[tex]\bold{DOMAIN:}\ 3\leq x<6\Rightarrow x\in[3;\ 6)\\\\\bold{RANGE:}\ 1<y<5\Rightarrow y\in(1;\ 5)[/tex]
Function? NOT, because for x∈(3, 5) the relation has two values of y.
The vertical line test.
If the vertical line you drew intersects the graph more than once for any value of x then the graph is not the graph of a function (picture 2).
