Solving A+b*sqrt2=c with Positive Rationals

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In summary, the conversation discusses the best way to solve a question involving finding two positive rational numbers a and b given an irrational number c, where a + b*sqrt2 equals c. The problem is proven to generally not have a solution, as shown by the example of there being no rational numbers a and b that can add up to an irrational number like pi.
  • #1
madah12
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Homework Statement



what's the best way solving question of finding two positive rational a and b given c
where a +b*sqrt2= an irrational number c


Homework Equations





The Attempt at a Solution

 
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  • #2


when you multiply an irrational number by a rational one, as you are doing here, which type of number is/can be the product? When you add...

Prove it, using the definitions.
 
  • #3


In general, such a problem will NOT have a solution. For example, there exist no rational a, b, such that [itex]a+ b\sqrt{2}= \pi[/itex].
 
  • #4


HallsofIvy said:
In general, such a problem will NOT have a solution. For example, there exist no rational a, b, such that [itex]a+ b\sqrt{2}= \pi[/itex].

I was taking "an irrational number c" to mean some irrational number c in which case there is quite some scope. What math level would be necessary to be able to prove your example?
 

Related to Solving A+b*sqrt2=c with Positive Rationals

1. What is the purpose of solving A+b*sqrt2=c with Positive Rationals?

The purpose of solving this equation is to find the values of A and b (positive rational numbers) that will make the equation true when multiplied by the irrational number sqrt2. This type of equation is common in mathematics and can be used to simplify expressions or solve real-world problems.

2. Is it possible to solve A+b*sqrt2=c with Positive Rationals?

Yes, it is possible to solve this equation with positive rational numbers. However, the solutions may not always be unique and may require some trial and error to find the correct values for A and b.

3. What is the process for solving A+b*sqrt2=c with Positive Rationals?

The process for solving this equation involves isolating the irrational term (sqrt2) on one side of the equation and the rational terms (A and b) on the other side. Then, using properties of rational and irrational numbers, we can manipulate the equation to solve for the values of A and b.

4. Are there any restrictions on the values of A and b in this equation?

Yes, in order for the equation to have a positive rational solution, A and b must be positive rational numbers. If either of these values is negative or irrational, the equation will not have a positive rational solution.

5. How can solving A+b*sqrt2=c with Positive Rationals be applied in real life?

This type of equation can be used in various real-world applications, such as calculating the diagonal of a square with rational side lengths, finding the hypotenuse of a right triangle with rational side lengths, or solving problems in geometry or physics that involve irrational numbers.

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