I believe it is 1. Function 2. Not a function 3. Function 4. Not a function. I hope this helps! :)
Answer:
Step-by-step explanation:

Answer:
To do this, you imagine a vertical (up and down) line moving across your graph from left to right. It should only be touching the line at one point at a time. If it is touching more than one point on the line at a time, the line is not a valid function. The first line and its inverse both pass the test.
Step-by-step explanation:
Answer:
The first four terms of the series are

= 14.25
Step-by-step explanation:
We know that
Sum of convergent series is also a convergent series.
We know that,

If the common ratio of a sequence |r| <1 then it is a convergent series.
The sum of the series is 
Given series,


The first four terms of the series are

Let
and 
Now for
,


It is a geometric series.
The common ratio of
is
The sum of the series



=10.5
Now for 


It is a geometric series.
The common ratio of
is
The sum of the series



=3.75
The sum of the series is 
= 
=10.5+3.75
=14.25