Answer:
A function is defined as an operation on a number, which gives only one output for every input
while graphing a function, the x-ordinate denotes the input and the y-ordinate denotes the output of the function
Now, lets look at the graph
for the input value '4' , we notice that there are 2 possible outputs. The output can be either 2.5 or -2.5
Since there are multiple outputs for almost every input, this graph cannot denote a function since a function gives only one output
