Is every relation a function?
No; some relations repeat inputs.
Evaluate f(x)=-3x for f(2).
What is -6?
Write all the ordered pairs shown in the mapping diagram below. 
(10, 15), (20, 45), (30, 25), and (40, 35)
Evaluate f(x)=2x+1 for f(-2).
What is -3?
Look at the table shown below:

What is the domain and range of this table?
Domain: {-2, 0, 4, 5}
Range: {14, 6, -10, -14}
Evaluate f(x)=-3 - x for f(6).
What is -9?
Look at the table below:
There's a question mark for one of the inputs. Which values could you put in that spot to make this NOT a function? (List all four values!)
32, 14, -2, and -10 (anything that would cause a repeated input).
| x | y |
| 2 | 4 |
| 1 | 5 |
| 2 | 6 |
Evaluate f(x)=25 + 4x for f(5).
What is 45?
Is this mapping diagram an example of a function?

Yes; the domain does not repeat
Evaluate f(x)=-(4x+2) for f(7).
What is -30
Is this relation a function? Explain why (An answer of just "yes" or "no", without reasoning, will earn only half the points if correct).

This is not a function. Each input should have exactly one output - but there are some inputs that have no outputs.