Yes they do. Have you read the manual?
You are correct with the above ^
Also, one of the splits at the end of the cable should have a few - - - - markings. I took that to mean negative.
They might work, but they might also be out of phase if you've wired them up incorrectly. It won't do any damage, but it'll play subtle hell with your sound.
See the response from "ChrisWiggles" in the following thread for a nice explanation:
http://www.hometheaterforum.com/htf/basics/248787-wiring-speakers-out-phase.html#post3049905