Are you asking if you should run your keyboard into a bass amp? I'd say no, the range of notes on a keyboard far outdoes the range on a bass and I can not see them doing well together. I have a Motion Sound keyboard amp. It really is quite amazing. Built in leslie and all. Get one of those!
The only amp U need to use for a keyboard is a keyboard amp or a PA. The frequency range of a keyboard is going to include the entire audible sonic spectrum. And U will blow computer speakers and damage guitar or bass cabinets.
Its the sound system. Like if U play with a band. This would be what the rest of the band connects to and the sound comes out of the house speakers.
Computer speakers will be ok to get you going. Plug them into the headphone out. You might need an adaptor.