I did so well with Calc 1 and calc 2 but the minute I took calc 3, I don’t know what happen. I 'm not catching up to the speed of the class. We’re about to leave vectors now… Can someone give me the essential concepts about vectors that I should know about? My textbook doesn’t make sense to me and I’m just struggling. I understand and do math at a slower pace than most people. I think I’m stupid.
I suggest posting this in the Math/Computer Science Majors forum. Also, you might find what is said at http://talk.collegeconfidential.com/university-north-carolina-chapel-hill/1519407-calculus-3.html useful.
Have you tried seeing if your school offers math tutoring services? They might have peer tutors or grad students who could help you catch up. You can also ask your TA or professor if they know of any resources that can help you. They may not be able to give you tons of one-on-one help if you have a lot of catching up to do, but they may be able to point you towards resources, help you get back on track, and answer questions you have about the lecture, homework, or reading.
There are also resources available online that might be more understandable than your textbook. I’ve never used it but Khan Academy includes sections on calculus. You will likely also be able to find some help by just googling topics that you are having trouble with.