I found some very poor PC program to do the graphs here. But I'd much prefer getting my calculator in order.
I think this would also be a nice place to discuss other investigation related stuff such as what to write in the investigation.
I'm thinking its important to define in what cases the quartic will actually be a "W" shape. (f"(x) the discriminant has to be bigger than 0..?) And just provide some "W" shapes looking down, etc. And tryyy to present it in a general form.