Hello everyone. I'm new here. I have a practice test that I'm working on for my linear algebra class and I sorta get the gist of determining whether or not something is a subspace or not but I'm having trouble with this one:

I did terrible in Calc 2 so the whole derivative thing isn't too familiar to me.

http://www.mathhelpforum.com/math-he...1&d=1267259282