I also struggled at first semester in college (I'm in my 3rd year now) with math (particularly Calculus) and found after my first semester it was due to a gap in my knowledge. I did not have a solid enough understanding of trig or high level algebra to calculate or manipulate equations expected of me so I would bomb all the exams.
If you can't fully understand low level concepts how can you even expect to even grasp the broader view? It's like trying to explain multiplication to someone who has no concept of addition. To understand a topic you must also understand all the sub-topics that make it up, and once you grasp all the moving parts a problem by nature become much more intuitive to you. This also includes math equations, if you are expected to know an equation dont JUST memorize it but instead understand why its necessary, how to derive it, and when you can and can't use it. You'll be able to look at an equation/function/program and pull things out automatically just by looking at it that may have taken some time and work to conclude before. This is very similar to Scott Young's learning ideology that I also recommend reading up on. [1]
Therefore after that semester I took some time and reviewed my algebra and basically re-learned trig from the ground up (it was very weak). Calc and Calc2 came a lot easier to me after this.
In college you must continually fill these gaps in your knowledge as every professor is different and has different expectations in student's knowledge. I've got in the habit of taking topics(whether it be a CS topic, math formula, ect) that I don't fully understand and writing it at the top of a blank sheet of paper. I then just start writing as if I was explaining the topic to my girlfriend. You'll quickly figure out where your gaps are and then know what you need to work on (which may include writing one of those sub-topics on a blank sheet and starting from there).
[1] http://www.scotthyoung.com/blog/2007/03/29/studying-and-holi...