Modulus of a Sequence: How to Prove Nullness?

[rohan03]

I know in general how to prove if sequence is null or not . But here is my confusion
- method in the textbook I am reading - asks that to prove that any sequence is null we must show that for each ε>0, there is an integer N such that modulus of the given sequence is < ε, for all n>N

now I also understand this but my dilema is
taking modulu say for example given sequence is
{(1+(-1)^n)/(n+(-1)^n )}
taking modulus gives:
|(1+(-1)^n)/(n+(-1)^n )| is modulus 2/(n+1) ?

just not sure

 

[DonAntonio]

I know in general how to prove if sequence is null or not . But here is my confusion
- method in the textbook I am reading - asks that to prove that any sequence is null we must show that for each ε>0, there is an integer N such that modulus of the given sequence is < ε, for all n>N

now I also understand this but my dilema is
taking modulu say for example given sequence is
{(1+(-1)^n)/(n+(-1)^n )}
taking modulus gives:
|(1+(-1)^n)/(n+(-1)^n )| is modulus 2/(n+1) ?

just not sure

\left|\frac{1+(-1)^n}{n+(-1)^n}\right|=\left\{\begin{array}{cc}0\,&amp;\,if\,\,n\,\,is\,\,odd\\\frac{2}{n+1}\,&amp;\,if\,\,n\,\,is\,\,even\end{array}\right. , and of course the seq. begin with n=2.

DonAntonio

Ps. Of course, the absolute value has no relevance here...did you notice this?

 

[rohan03]

Yes the question states n=2,3... So I am correct and must ignore negative values of n