Quick question about inequality notation

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    Inequality Notation
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Discussion Overview

The discussion revolves around the correct use of inequality and equality notation in mathematical expressions, specifically in the context of a given value for x. Participants explore when it is appropriate to switch from inequality to equality and the conventions regarding the use of comparison symbols in mathematical writing.

Discussion Character

  • Conceptual clarification, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant asks which of two forms of notation is correct when x = 4, questioning the necessity of switching from inequality to equality.
  • Another participant suggests that the decision to switch from inequality to equality depends on personal writing style, noting that multiple comparison symbols per line are common in textbooks.
  • A third participant clarifies the logical interpretation of "A or B" in the context of inequalities, stating that both "4 ≤ 4" and "4 = 4" can be considered true.
  • One participant agrees that both examples presented are correct but indicates that the second example is more commonly seen in practice.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of switching from inequality to equality and the conventions regarding comparison symbols, indicating that there is no consensus on these points.

Contextual Notes

The discussion does not resolve the conditions under which switching from inequality to equality is necessary, nor does it clarify the implications of using multiple comparison symbols in mathematical writing.

quark1005
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Which of the following is correct, if x = 4?

[tex]n\leq3x^{2}[/tex]

[tex]\leq3(4)^{2}[/tex]

[tex]\leq48[/tex]

or

[tex]n\leq3x^{2}[/tex] [tex]=3(4)^{2}[/tex] [tex]=48[/tex]

In other words, in what situations is it necessary to switch from inequality to equality, and it is always required to have only one comparison symbol per line?
 
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quark1005 said:
In other words, in what situations is it necessary to switch from inequality to equality, and it is always required to have only one comparison symbol per line?
It really depends on your writing style. Every maths textbook I've seen puts multiple comparison symbols per line, so it's not a big deal if you do so.
 
"A or B" is true if either A or B is true. In particular "[itex]4\le 4[/itex]" means "4< 4 or 4= 4". Since the latter is true [itex]4\le 4[/itex] is true. Of course, it is more precise to say "4 = 4" but both are true.
 
Both of your examples are correct, but the second one is the one usually seen.
 

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