How do you connect a home theater sub-woofer that has left and right rca inputs?

Question

the reciever has only the standard one chanel (one rca) out for the sub.

Answer 1

Just plug the sub-out from the receiver into either of the two inputs on the sub, leaving the other unconnected.

--or--

Use a splitter to send the signal to both.

Doesn't make a difference wither way.

Answer 2

You could do it one of two ways.  Either plug the cable from the receiver into the right or left plug ins of your sub.  Some subs have it marked to input into the left one for single line.  

Or you could get a y-splitter that has a single female input connector and two male connectors to plug into the sub.