I have a bluetooth mouse & keyboard (Dell KM714) that don't seem to be recognized by Ubuntu 14.10. They don't appear in the list of bluetooth devices when I am looking for them.
Is there a way to make them work together?
Have you tried Blueman?
It has many more drivers for additional devices than the normal bluetooth.
sudo apt-get install blueman and see if using that fixes your problem.
I know that using this manager instead of the original has worked to connect my bluetooth keyboard originally designed for my iPad.
Edit: The actual solution:
The Dell KM714 Keyboard no Mouse set are not in fact Bluetooth capable. They are controlled by a wireless USB Dongle that should have come with the product.
If you do not have the USB dongle, you may not be able to use this mouse and keyboard.