I wasn't sure if to post this in the Calculus forum or in the Algebra forum. My question has more to do with the algebra than it does with the calculus part however since it is a limit question I thought it would be better to post to the Calculus forum.

It looks to me by looking at the graph that as x->infinity that y-> -infinity. Problem f) seems to be solved positive infinity? I'm still trying to figure out the algebra that I highlighted I don't see yet how those are equivalent. Also I was wondering am I supposed to know the answer to f) without looking at its graph or how if that is possible?

Thanks in advance...