Simple inequalities question I promise

  • Thread starter Thread starter smashbrohamme
  • Start date Start date
  • Tags Tags
    Inequalities
Click For Summary

Homework Help Overview

The discussion revolves around solving the inequality (x+2)/(x+4) ≥ 1, with participants exploring the implications of different interpretations and simplifications of the expression.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants present various interpretations of the inequality, questioning the validity of proposed solutions and simplifications. There is an exploration of the conditions under which the inequality holds, as well as discussions about interval notation.

Discussion Status

The discussion is active, with participants offering insights and questioning each other's reasoning. Some have pointed out potential errors in simplifications, while others are clarifying the implications of the inequality and its conditions.

Contextual Notes

There are indications of confusion regarding the correct form of the inequality, as one participant acknowledges a typo that changes the problem's nature. Additionally, assumptions about the behavior of the fraction under certain conditions are being examined.

smashbrohamme
Messages
97
Reaction score
1
(x+2)/(x+4) greater or equal to 1.

I got two different answers here.

X is greater than 4.

Or a interval notation (-Infinite, 4) - which doesn't make sense but wouldn't the correct answer just be X is greater than 4?

which would mean (4, infinite)?

Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
if x = 5 then you'd get 7/9 which is not greater than or equal to one, so I think you messed up your simplification.

Post your working and see if you can find the error.
 
I think you just have a silly problem! For all x, x+ 2< x+ 4 so you have a fraction in which the denominator is larger than the numerator.
 
lol shoot! I made a silly typo...its (x+2)/(x-4) greater then or equal to 1
 
so how would you write that in interval notation, (4, Infinite)?
 
HallsofIvy said:
I think you just have a silly problem! For all x, x+ 2< x+ 4 so you have a fraction in which the denominator is larger than the numerator.

If x < -4, the inequality changes its direction, so that would be the solution...
 
[tex] \begin{align*}<br /> \frac{x+2}{x+4} \ge 1 \Leftrightarrow \\<br /> <br /> \frac{x+2}{x+4}-1 \ge 0 \Leftrightarrow \\<br /> <br /> \frac{(x+2)-(x+4)}{x+4} \ge 0 \Leftrightarrow \\<br /> <br /> \frac{x+2-x-4}{x+4} \ge 0 \Leftrightarrow \\<br /> <br /> \frac{-2}{x+4} \ge 0<br /> \end{align*}[/tex]

When does this inequality hold, i.e. when is the ratio of a negative number and another one nonnegative?
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
8
Views
5K
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
3
Views
3K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K