i'm working on my homework right now and there is 1 problem i'm having a little trouble with...just wondering if someone can point me in the right direction or possibly unconfuse me...it seems easy, i think i might just be going about it in the wrong way question: how many bit strings of length n, where n is a positive integer, start and end with 1s? would it just be n/4?

n/4 isn't right. You're sort of on the right track though. Think about when n=3. Can you really have .75 different bit strings? Do some trial and error. For any n, there are 2^n possible strings. For example, when n=2, there are 2^2 (or 4) possible bit strings: 00 01 10 11 and exactly 1 of them begins and ends with 1. Try all the possible combinations when n=3, 4, and 5 and see what you can come up with. I really can't give you more without actually giving you the answer.

ok...just went through the rest and there are a couple others i can't figure out 1. show that if n is a positive integer, then (2n,2) = 2(n,2) + n^2 by algebraic manipulation now when i say (2n,2) i mean (2n) (2 ) except in just one pair of tall parenthesis...as in the 2n is above the 2...and same with the n,2 2. how many subsets with an odd number of elements does a set with ten elements have? 3. how many ways are there for ten women and six men to stand in a line so that no two men stand next to each other? (hint: first position the women and then consider possible positions for the men) this one i am just not sure if my answer is right i got 11!/(6!5!)=462...seemed kinda high to me so i just wanted to double check thanks for any help in advance

Man, I'm gonna be completely honest with you, I had discrete math probably 10 years ago, and I made it through 1 week before I dropped and changed majors... good luck.

discrete isn't anything compared to my principles of computer organization class...if i was still a freshman or sophmore, i'd be changing majors because of that class