Proving the Triangle Inequality for Real Numbers

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SUMMARY

The discussion centers on proving the Triangle Inequality for real numbers, specifically the statement that for real numbers x(1), x(2), ..., x(n), the inequality |x(1) + x(2) + ... + x(n)| <= |x(1)| + ... + |x(n)| holds true. Participants suggest starting with the foundational inequality |a + b| <= |a| + |b| and generalizing it to multiple terms. The conversation emphasizes the importance of establishing the base case and then extending the proof to n terms using mathematical induction or direct application of the inequality.

PREREQUISITES
  • Understanding of real numbers and absolute values
  • Familiarity with basic properties of inequalities
  • Knowledge of mathematical induction
  • Ability to manipulate algebraic expressions
NEXT STEPS
  • Study the proof of the Triangle Inequality for two real numbers
  • Learn about mathematical induction techniques
  • Explore generalizations of inequalities in real analysis
  • Investigate applications of the Triangle Inequality in various mathematical contexts
USEFUL FOR

Students studying real analysis, mathematicians interested in inequalities, and educators teaching foundational concepts in mathematics.

Fairy111
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Homework Statement



For real numbers x(1), x(2), ..., x(n), prove that |x(1) + x(2) +...+x(n)| <= |x(1)|+...|(n)|

Homework Equations


The Attempt at a Solution

Maybe begin with prooving that x <= |x| ? I am not sure how to do this though.
Any help or hints would be great, as I am really stuck on this.
 
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Fairy111 said:

Homework Statement



For real numbers x(1), x(2), ..., x(n), prove that |x(1) + x(2) +...+x(n)| <= |x(1)|+...|(n)|

First of all, one can prove that, for some real numbers a, b, |a + b| <= |a| + |b|. Any ideas how to generalize? Try to use this inequality to show that |a + b + c| <= |a| + |b| + |c|, for some given real numbers, a, b and c.
 

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