Is My Graphing Method for (1/x)<x<1 Correct?

  • Context: Undergrad 
  • Thread starter Thread starter garyljc
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Discussion Overview

The discussion revolves around the inequality (1/x) < x < 1, with participants exploring methods for graphing and solving the inequality. The scope includes mathematical reasoning and technical explanation regarding the solution set.

Discussion Character

  • Mathematical reasoning, Technical explanation, Debate/contested

Main Points Raised

  • One participant initially suggests that the solution is -1 < x < 1 based on their graphing method.
  • Another participant claims that the equation does not have a solution set, arguing that the steps lead to x^2 > 1 and x < 1, which they believe implies no solution.
  • A third participant challenges the reasoning of the second participant, hinting at a potential flaw in their logic regarding the multiplication of inequalities.
  • A fourth participant provides a detailed breakdown of the inequality, concluding that the solution is -1 < x < 0, while also noting the conditions under which this applies.
  • A fifth participant expresses gratitude to others for their contributions, indicating engagement with the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the solution to the inequality, with multiple competing views presented regarding the correct solution set.

Contextual Notes

The discussion includes various assumptions and methods for solving the inequality, with some steps remaining unresolved or dependent on specific interpretations of the inequalities involved.

garyljc
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Hi all ,
could someone help me out with this
(1/x)<x<1

i tried by drawing the graphs
and separated it in 2 equations
but the answer that i found was -1<x<1
is it correct ?
 
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this equation does not have a solution set

correct me if I'm wrong
if first do the first 2 steps of the equation ,it follows that 1/x < x
therefore x^2>1
second equation will be that x<1
therefore there is no solution
am i correct ?
 
Hi garyljc! :smile:
garyljc said:
1/x < x
therefore x^2>1

am i correct ?

Nope! :smile:

Hint: If a < b and c < 0, is ac < bc? :wink:
 
1/x<x
1/x - x<0
(1-x^2)/x<0
(x^2 - 1)/x>0

case 1: numerator and denominator are positive
numerator
x^2-1>0
(x+1)(x-1)>0
By wavy curve method
x<-1 or x>1
denominator
x>0
so solution for this case is x>1
but x<1 (given in the question)
hence no solution in this case.

case 2: numerator and denominator are negative
x^2-1<0
(x+1)(x-1)<0
By wavy curve method
-1<x<1
x<0
so solution for this case is -1<x<0
but x<1
hence solution for this case is -1<x<0

SO THE ANSWER IS -1<X<0
 
thanks to both lizzie and tim
 

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