Pretty simple ordered field question

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In summary, the conversation discusses proving that multiplying a negative number through an inequality changes the inequality, using the equation ac < bc. The conversation also includes attempts at solving the problem and receiving hints before ultimately figuring out the solution.
  • #1
jaqueh
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Homework Statement


basically proving multiplying a negative number through an inequality changes the inequality


Homework Equations


if a > b, and c < 0,
then the following inequality holds: ac < bc.


The Attempt at a Solution


I am pretty stumped on this one, i tried to prove that C is a negative number, but i don't know where to go at all
 
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  • #2
For the most part, it should be just unraveling definitions, and making use of the fact ad>bd for any positive d. (and picking a useful d)
 
  • #3
i'm still stuck, all i can think of is making the d=-c which i define when c+(-c)=0
 
  • #4
i'm still lost, i don't know why i am so bad at simple algebraic manipulations. can anyone offer more hints?
 
  • #5
jaqueh said:
i'm still stuck, all i can think of is making the d=-c which i define when c+(-c)=0
So make the substitution. How is < defined? Apply the definition both to this case, and to the case you're trying to solve, so that you can see what you need to prove.
 
  • #6
I actually ended up figuring it out, thanks tho!
 
  • #7
jaqueh said:
I actually ended up figuring it out, thanks tho!

Ah good!
 

1. What is a pretty simple ordered field?

A pretty simple ordered field is a type of mathematical structure that satisfies certain properties, such as being able to add, subtract, multiply, and divide elements within the field. It is called "ordered" because the elements in the field can be arranged in a specific order, and it is considered "pretty simple" because it follows a straightforward set of rules.

2. How is a pretty simple ordered field different from a regular field?

A pretty simple ordered field is a specific type of field that follows additional rules, such as being able to arrange its elements in a specific order. A regular field, on the other hand, may not have this ordering property or may follow different rules altogether.

3. What are some examples of pretty simple ordered fields?

Some common examples of pretty simple ordered fields include the set of rational numbers, real numbers, and complex numbers. These sets follow the necessary properties and can be arranged in a specific order.

4. What are the properties of a pretty simple ordered field?

A pretty simple ordered field must have certain properties, including closure under addition, subtraction, multiplication, and division, as well as the existence of an identity element for addition and multiplication, and the existence of inverse elements for addition and multiplication.

5. What are the applications of pretty simple ordered fields?

Pretty simple ordered fields have various applications in mathematics, such as in algebra, geometry, and analysis. They are also commonly used in economics, physics, and engineering for modeling and solving real-world problems.

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