Prove if a belongs R, then (a^2)^1/2= |a|?

  • Context: Undergrad 
  • Thread starter Thread starter hugo28
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Discussion Overview

The discussion revolves around proving the mathematical statement that if \( a \) belongs to the real numbers \( \mathbb{R} \), then \( (a^2)^{1/2} = |a| \). The scope includes algebraic reasoning and definitions related to square roots.

Discussion Character

  • Homework-related, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant requests assistance in proving the statement and presents an initial attempt involving inequalities.
  • Another participant notes that the proof depends on the definition of the square root, mentioning that the usual definition yields two answers, \( a \) and \( -a \), unless the square root is defined to be positive.
  • A third participant asserts that if \( a \geq 0 \), the statement is obvious, but suggests considering \( -a \) for the case when \( a < 0 \).
  • A later reply indicates that the thread was closed due to the original poster not showing sufficient work.

Areas of Agreement / Disagreement

Participants express differing views on the definition of the square root and its implications for the proof. The discussion does not reach a consensus on the proof or the definitions involved.

Contextual Notes

The discussion highlights the dependence on the definition of the square root and the implications of considering both positive and negative values of \( a \). There is also an indication of incomplete work from the original poster, which may affect the clarity of the discussion.

hugo28
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Would you please help me? Thanks in advance.

Prove that if a belongs to R, then (a^2)^1/2 = |a|?
by using Abstract, Discrete, Algebraic Math.

I work, but stuck:
|a| =< (a^2)^1/2, then
- (a^2)=< a =< (a^2)

Please help!
 
Last edited:
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Depends on your definition of square root. The usual definition means you will have two answers a and -a. However if you insist that the square root be positive, the |a| is the positive root.
 
If a >= 0, it's pretty much obvious; otherwise, consider -a.
 
Thread closed for user not showing any work.
 

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