Can I attach subwoofers to a 2-channel amp in line with coaxial speakers?

Now, to be fair, I'm not actual putting this in a car yet, I'm just putting together a system from car audio components. (I'll move on to putting it in my car when I really want to make the investment, and when I understand what I'm doing a bit more.)

But yeah, can I connect a subwoofer or two with some coaxial speakers into a two channel amp?

The coaxials seem like they handle the mid and high range alright, but I really want that bass. From what I understand of the electronics it seems like it should work.