how can u tell if something is a function

Answer:
To know if it is a function see if there are two of the same x-intercept( which makes a vertical line). If there is,then it is not a function.
Answer:
How you can tell
Step-by-step explanation:
A function assigns exactly one output to each input: x/input y/output
How they work: X can not repeat but Y can.
Lets see your problem, there are no inputs repeating and the outputs are fine.
That is a function!