Question

How do I graph a cost function like `C(x) = 3x + 20,000`?

Answer 1

I think that your function can be used to model a service (say a health insurance) where you pay a fixed value (20,000) to join the program and 3 for each medical visit.

Explanation:

Your function is a linear function and is represented, graphically, by a straight line.

Considering an example you can immagine that it represents a medical insurance.

You pay `$20,000` to join in and then you pay `$3` for each visit: you can plot your function by using some values of `x` and calculating the corresponding `C`:

For example:
`x=0, C(0)=0+20,000=20,000`
`x=1, C(1)=3+20,000=20,003`
`x=2, C(2)=6+20,000=20,006`
...etc.

You can now plot these points on your graph.
So, graphically you have: