Find the following limit as x->0

  • Context: Undergrad 
  • Thread starter Thread starter thenewbosco
  • Start date Start date
  • Tags Tags
    Limit
Click For Summary

Discussion Overview

The discussion revolves around finding the limit of the expression \(\frac{\sin x - x}{\sin^3(x)}\) as \(x\) approaches 0. Participants explore various methods for evaluating this limit, including L'Hôpital's rule and algebraic manipulation.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant initially struggles with the limit and mentions that L'Hôpital's rule leads to a more complex expression.
  • Another participant suggests applying L'Hôpital's rule again and multiplying the expression by \(\frac{\cos(x)+1}{\cos(x)+1}\) to simplify it.
  • There is a question raised about how to know when to use specific algebraic manipulations in similar limit problems.
  • Some participants mention that practice and familiarity with mathematical techniques can help in recognizing useful manipulations.
  • Another participant notes that factoring the denominator after converting \(\sin^2\) to \(\cos^2\) could also be a viable approach.

Areas of Agreement / Disagreement

Participants express differing opinions on the best approach to take for solving the limit, with some advocating for repeated application of L'Hôpital's rule while others suggest algebraic manipulation. No consensus is reached on a single method being superior.

Contextual Notes

Participants do not fully resolve the steps involved in applying L'Hôpital's rule or the implications of the algebraic manipulations suggested, leaving some assumptions and methods unexamined.

Who May Find This Useful

Students or individuals interested in calculus, particularly those looking for strategies to evaluate limits involving trigonometric functions.

thenewbosco
Messages
185
Reaction score
0
find the following limit as x-->0

Hello I am trying to find the following limit as x-->0. I have tried using l'hopital's rule but all it produces is a more complex thing i still can't take the limit of. any help?
[tex]\frac{sin x - x}{sin^3(x)}[/tex]
I can see this limit exists on the graph i just don't know how to go about solving it.
 
Physics news on Phys.org
Take L'hopital once.
Then multiply your expression with [tex]1=\frac{\cos(x)+1}{\cos(x)+1}[/tex]
 
Thanks this worked. One question about this is how did you know to multiply by this? How would one know to do this when faced with similar situations
 
You could have just done L'Hôpital again.

arildno just factored the denominator (after converting sin² to cos²).
 
thenewbosco said:
Thanks this worked. One question about this is how did you know to multiply by this? How would one know to do this when faced with similar situations
Just practice&patience.
To think of simple tricks like this comes naturally to you if you have worked assiduously with your maths earlier.
 
Hurkyl said:
You could have just done L'Hôpital again.

arildno just factored the denominator (after converting sin² to cos²).
Factorization is more fun.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
3
Views
2K
Replies
4
Views
2K