Answer:
The biggest differentiating factor between a function and NOT a function
is that a function gives only one output for any given input. so no matter how many times you use the same value in the function, you will get the same output
A relation which is not a function will have 2 or more outputs for a single input
So if we have more than 1 similar input values in the table and given them different outputs, the relation will NOT be a function
I will take 2 similar inputs "1" and give them different outputs, the rest of the table can be randomly filled
x y
1 4
3 7
5 9
1 2