# Homework Help: Determine whether the sequences are increasing

1. Nov 4, 2007

### will_lansing

1. The problem statement, all variables and given/known data
Determine whether the sequences are increasing, decreasing, or not monotonic.
1) an= $$\frac{\sqrt{n+2}}{4n+2}$$
2) an=$$\frac{1}{4n+2}$$
3) an=$$\frac{cosn}{2^{n}}$$
4) an=$$\frac{n-2}{n+2}$$
2. Relevant equations

3. The attempt at a solution
I thought that the number 1 and 2 were decreasing because $$a_{n}$$ $$\geq$$ $$a_{n+1}$$ in both cases
#3 is increasing because $$a_{n}$$$$\leq$$ $$a_{n+1}$$
#4 is monotonic because if n=3 then its 0

for number #1 I compared it to $$a_{n+1}$$=$$\frac{\sqrt{n+3}}{4n+6}$$
and i found that it was smaller than an so it was decreasing
i did this procedure for the rest of them and i still get the wrong answer