Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Prove that the ff. sequence are null. a. {1/n^2 +n} b. {(-1)^n /n!} c. {sin n^2 / n^2 +2n} d. { 1/ 3n^4 (2n-1)^1/3

A $\LaTeX$ interpretation of you sequence: \begin{align*} a_n &= \frac{1}{n^2+n}\\ b_n &= \frac{(-1)^n }{n!}\\ c_n&= \frac{\sin(n^2)}{n^2+2n}\\ d_n&=\frac{1}{3n^4 \sqrt[3]{2n-1}} \end{align*}

share|improve this question
    
Do you have any idea how to do any of these yourself? any idea where to start? Is there some particular place where you get stuck? Is there some reason for your being interested in these particular problems? –  Gerry Myerson Mar 2 '13 at 12:05
    
I set your sequences in $\LaTeX$ please check if I did it right, I added the homework tag, please remove it, when it is no homework –  Dominic Michaelis Mar 2 '13 at 12:12
1  
@DominicMichaelis, Tnx for edit this post,It was very complicated. –  M.Sina Mar 2 '13 at 12:15
add comment

1 Answer

As it sounds pretty much like homework you will just get a hint:

Use comparism with other sequence and use $|\sin(x)|\leq 1 $ for all $x$.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.