Problem 1
With limits, you are looking to see what happens when x gets closer to some value. For example, as x gets closer to x = 2 (from the left and right side), then y is getting closer and closer to y = 1/2. Therefore the limiting value is 1/2
Another example: as x gets closer to x = 4 from the right hand side, the y value gets closer to y = 4. This y value is different if you approach x = 0 from the left side (y would approach y = 1/2)
Use examples like this and you'll get the results you see in "figure 1"
For any function values, you'll look for actual points on the graph. A point does not exist if there is an open circle. There is an open circle at x = 2 for instance, so that's why f(2) = UND. On the other hand, f(0) is defined and it is equal to 4 as the point (0,4) is on the function curve.
=======================================================
Problem 2
This is basically an extension of problem 1. The same idea applies. See "figure 2" (in the attached images) for the answers. 
 
        
        
        
Answer:
1. Linear
2. Linear
3. Non-Linear
4. Non-Linear
5. Linear
6. Non-Linear
7. Linear
8. Non-Linear
9. Linear
The code should be LLNNLNLNL
 
        
                    
             
        
        
        
Answer:
A. The temperature outisde and the number of people swimming at the beach. 
Step-by-step explanation:
As the temperature decreases the number of people swimming will also decrease. This will create a negative correlation between the two factors. 
 
        
             
        
        
        
Answer:
y = -2x^2 - 4x - 1
Step-by-step explanation:
We can see that the graph passes through (-2, -1), (-1, 1) and (0, -1).
Let's solve
ax^2 + bx + c = y
a(-2)^2 + b(-2) + c = -1
4a - 2b + c = -1
a(-1)^2 + b(-1) + c = 1
a - b + c = 1
a0^2 + b0 + c = -1
c = -1
we got c = -1 so we input it into the other 2
4a - 2b - 1 = -1
4a - 2b = 0
2a - b = 0
2a = b
a - b - 1 = 1
a - b = 2
a = b + 2
Let's input b = 2a
a = 2a + 2
-a = 2
a = -2
b = 2a = 2*(-2) = -4
c = -1
y = -2x^2 - 4x - 1
 
        
             
        
        
        
Look at 36/3 = 12.  
So let's try 12 along with the one before it and the one after it.
10 + 12 + 14 = 36
yay !