Question

Is anyone taking Pre Calculus that can explain graph functions?

Answer 1

Explain what exactly? Graphing a particular function?

Sorry - what's the question?

Answer 2

The question asks which graph is a function? And I'm not sure how to figure that out.

Answer 3

Ah, ok.... we can work with that. Here's what you need to know: in order for a relation (which is just a set of (x,y) pairs, that's what the graphs are "drawing") to be a function, it has to be true that there is ONLY ONE Y for EACH X. The way I explain it is:

If it's a function, it has to be true that IF YOU KNOW X, YOU KNOW Y.

It can't be the case that one x "maps" to two different y's.

Follow so far?

Answer 4

I think so

Answer 5

When looking at a graph, an easy way to "test" this is called the "vertical line test" which goes like this: if it is a function, then each vertical line in the plane crosses the graph, AT MOST, at ONE point on the graph. Otherwise, you have one x that is matched to 2 different y's. example: