How do I determine a function in a graph?

Question

anonymous · Answer

vertical line test

anonymous · Answer

trace a vertical line
it always it touches the graph in one point then it is a fuinction

anonymous · Answer

As julian said that is the easiest way to do it. Remember that in order for an equation or a graph to be a function, x must have only 1 y value. y can have 2 x values and it would still be a funtion but if x has two y values it is not a function.

anonymous · Answer

@Tehsh Im not understandg the concept of drawing a vertical line. I have 4 answers to chose from and a graph to look at. However, I cannot upload a picture of the graph.

anonymous · Answer

Can you type the question and the answer choices?

anonymous · Answer

Its not a question, thats the problem. It gives me a picture of a graph and says to determine which function is in the graph. It then provides me with 4 answer choices. @Tehsh

anonymous · Answer

Here if you don't understand the concept I'll show you.|dw:1373463516928:dw|