How can I solve a one-sided limit without using l'Hopital's rule?

Click For Summary

Homework Help Overview

The problem involves evaluating the one-sided limit as x approaches -1 from the right for the expression involving a square root and an absolute value in the denominator.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of l'Hôpital's rule and express a desire to find alternative methods for solving the limit. Suggestions include multiplying by the conjugate of the numerator and addressing the absolute value in the denominator based on the direction of the limit.

Discussion Status

Participants are exploring different approaches to the limit, with some providing guidance on how to manipulate the expression without using l'Hôpital's rule. There is an acknowledgment of the need to clarify the expression and the conditions under which the absolute value can be simplified.

Contextual Notes

There is a focus on the behavior of the expression as x approaches -1 from the right, particularly regarding the treatment of the absolute value and the square root. Some participants express uncertainty about the notation used in the limit statement.

squirrelschaser
Messages
14
Reaction score
0

Homework Statement

Find the ## lim _{x-> -1+} sqrt(x^2-3x)-2/|x+1| ##

Homework Equations

The Attempt at a Solution



I can only solve it using l'hopital rule and would like to know the steps of solving it without using it.

## lim _{x->-1+} (2x-3)/|1|= -5/4 ##
 
Physics news on Phys.org
squirrelschaser said:

Homework Statement

Find the ## lim _{x-> -1+} sqrt(x^2-3x)-2/|x+1| ##

Homework Equations

The Attempt at a Solution



I can only solve it using l'hopital rule and would like to know the steps of solving it without using it.

## lim _{x->-1+} (2x-3)/|1|= -5/4 ##
Multiply the expression by 1 in the form of the conjugate of the numerator over itself. The |x + 1| factor in the denominator can be replaced by x + 1, since x is to the right of -1, so x + 1 > 0. If the limit had been as x approaches -1 from the left you have to replace |x + 1| by -(x + 1).
 
squirrelschaser said:

Homework Statement

Find the ## lim _{x-> -1+} sqrt(x^2-3x)-2/|x+1| ##

Homework Equations

The Attempt at a Solution



I can only solve it using l'hopital rule and would like to know the steps of solving it without using it.

## lim _{x->-1+} (2x-3)/|1|= -5/4 ##

I suppose you mean$$
\lim_{x\to -1^+}\frac{\sqrt{x^2-3x}-2}{|x+1|}$$which is not what you wrote. Anyway since ##x>-1## you can write ##|x+1|=x+1##. Try rationalizing the numerator and see if you can get it then.

[Edit] Mark44 must type faster than I do.
 
Last edited:
I'm dumb. Much thanks.
 
No, you are careless- that, at least, is curable!
 

Similar threads

Replies
1
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 21 ·
Replies
21
Views
7K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
7K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K