Proving the Triangle Inequality for Real Numbers

In summary, the task is to prove that for real numbers x(1), x(2), ..., x(n), the absolute value of their sum is less than or equal to the sum of their absolute values. This can be generalized by using the property that for any real numbers a and b, |a + b| <= |a| + |b|.
  • #1
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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  • #2
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.
 

FAQ: Proving the Triangle Inequality for Real Numbers

1. What are real numbers?

Real numbers are numbers that can be found on the number line and include positive and negative whole numbers, fractions, decimals, and irrational numbers like pi and square root of 2.

2. How do you prove a statement using real numbers?

To prove a statement using real numbers, you must provide evidence or logical steps that show the statement is true for all real numbers. This can include using algebraic equations, geometric proofs, or logical reasoning.

3. Can you give an example of a proof with real numbers?

Yes, for example, to prove that the sum of two even numbers is always an even number, we can use real numbers such as 4 and 6. The sum of 4 and 6 is 10, which is also an even number. This holds true for all even numbers, therefore the statement is proven.

4. What is the importance of proofs with real numbers?

Proofs with real numbers are important in mathematics and science because they provide a way to validate theories and statements. They allow us to show that a statement is true for all possible values of real numbers and can help us make predictions and solve problems.

5. Are there any limitations to proofs with real numbers?

Yes, there are limitations to proofs with real numbers. They may not apply to all situations, such as when dealing with complex or imaginary numbers. Additionally, some statements may be difficult or impossible to prove using real numbers alone and may require other mathematical concepts.

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