Help me please!! I know what a function actually is, I just don’t understand how to get it through equations like this. I just need a few to be broken down so I can understand this. Thank you :)

Which equation represents the function on the graph?

Which of the following is the result of expanding the series

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.