Proving MAX[a,b] and MIN[a,b] with Real Numbers: A Proof Question

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In summary, the conversation discusses proving that max[a,b] = (1/2)(a+ b+ |a- b|) for two real numbers a and b. The concept of maximum and minimum is defined and the approach to proving the equation is explained, breaking it down into two cases based on the value of a compared to b. The conversation also mentions using absolute value and discusses a possible approach to the proof.
  • #1
transgalactic
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for "a" and "b" are real numbers prove that:
http://img505.imageshack.us/img505/5329/26310844lw6.gif

whats the meaning of MAX[a,b] and MIN[a,b]

how am i supposed to prove that
??
 
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  • #2
Max[a, b] is "maximum of a and b" or simply the larger of the two numbers.

You are asked to prove that max[a,b] = (1/2)(a+ b+ |a- b|)

As always with absolute value problems, break it into to cases: a> b and a< b, and show that the two sides are the same in each of those cases.
 
  • #3
but there are variables
even if i presume that a>b
i can't develop into a formula
i can't put it into the given expression
??
 
  • #4
the only thing i can do with the given expression
is to split |a- b| into two cases
a-b>0 ->a>b
which gives me :
(1/2)(a+ b+ a- b)=a

a-b<0 a<b:
(1/2)(a+ b-a+ b)=bi got a similar resolt but it didnt came from
that in the i say "if a>b ..."
 
  • #5
transgalactic said:
the only thing i can do with the given expression
is to split |a- b| into two cases
a-b>0 ->a>b
which gives me :
(1/2)(a+ b+ a- b)=a

a-b<0 a<b:
(1/2)(a+ b-a+ b)=b

That's a proof, isn't it?

What's wrong with that? :confused:

(and why didn't you type out the question, and make it easier for every one?)
 
  • #6
in the first post i typed the question and added a link to the formula

regarding the question:
i did it correctly?
 

1. What is the definition of MAX[a,b] and MIN[a,b] in mathematics?

MAX[a,b] refers to the maximum value between two numbers, a and b. It is the larger of the two numbers. MIN[a,b] refers to the minimum value between two numbers, a and b. It is the smaller of the two numbers.

2. How can we prove that MAX[a,b] and MIN[a,b] can be represented using real numbers?

We can prove this by using the axioms and properties of real numbers. For example, we can show that the maximum value between two numbers can be found by comparing their decimal representations and choosing the larger one. Similarly, the minimum value can be found by comparing decimal representations and choosing the smaller one.

3. Is there a specific formula or method to prove MAX[a,b] and MIN[a,b] with real numbers?

Yes, there are a few different methods that can be used to prove this. One method is by using the definition of maximum and minimum values and showing that they can be represented using real numbers. Another method is by using algebraic manipulations and properties of real numbers to show that the maximum and minimum values can be expressed using real numbers.

4. Can we prove MAX[a,b] and MIN[a,b] using only integers or rational numbers?

No, we cannot prove MAX[a,b] and MIN[a,b] using only integers or rational numbers. This is because the set of integers and rational numbers is not closed under maximum and minimum operations. In other words, there may be cases where the maximum or minimum value between two numbers is not an integer or a rational number.

5. Why is it important to prove MAX[a,b] and MIN[a,b] using real numbers?

Proving MAX[a,b] and MIN[a,b] using real numbers is important because real numbers are widely used in mathematics and in real-world applications. Real numbers have specific properties and axioms that make them useful for representing and manipulating quantities. By proving that MAX[a,b] and MIN[a,b] can be represented using real numbers, we can confidently use them in various mathematical equations and problems.

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