http://www.desmos.com/calculator

1. Type in the function.
2. Add text.
3. Copy and paste the function into text.
4. Copy the code.

At the top of the page:

1. Add Resource to Problem --> Text
2. Paste code into Text:
3. Click ok.
4. The resource will go to the bottom of the screen.

Note: You can't combine regular text with LaTex.

1. Go to the bottom of the screen where the resource is located.
2. Go to Edit --> Convert to LaTex
3. Go to Style --> Color  (Choose a background color.)