How Can I Solve √(6 + 3√2) = √a + √b for a and b?

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Homework Help Overview

The discussion revolves around solving the equation √(6 + 3√2) = √a + √b, with a and b expressed in the form a + b√c. Participants are examining the reasoning behind the assertion that a + b = 6 based on their attempts to manipulate the equation.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss squaring both sides of the equation and question how the conclusion a + b = 6 is reached. Some suggest that this might be a simplification rather than a definitive deduction from the equation.

Discussion Status

The conversation is ongoing, with participants recognizing that multiple solutions may exist. They are exploring different interpretations of the equation and considering alternative approaches to find solutions, while acknowledging the complexity of potential outcomes.

Contextual Notes

There is a focus on finding simple solutions, and participants express concern about the complexity of other potential solutions. The original problem context includes specific forms for a and b, which may influence the direction of the discussion.

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Homework Statement


Solve the equation √(6 + 3√2) = √a + √b, writing a and b in the form a + b√c.


Homework Equations


In the answers they say that a + b = 6, but I cannot see how they can say this.


The Attempt at a Solution


I square both sides, and that is as far as I get:
6 + 3√2 = a + 2√(ab) + b

In the answers, they say from here that a + b = 6. I am clueless as to how they can say this.
 
Last edited:
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BMW said:

Homework Statement


Solve the equation √(6 + 3√2) = √a + √b, writing a and b in the form a + b√c.

Homework Equations


In the answers they say that a + b = 6, but I cannot see how they can say this.

The Attempt at a Solution


I square both sides, and that is as far as I get:
6 + 3√2 = a + 2√(ab) + b

In the answers, they say from here that a + b = 6. I am clueless as to how they can say this.

I don't think they are deducing that from the equation. They are just saying 'let's look for a solution where a+b=6 and 3√2=2√(ab)'. If you can find simple numbers a and b that satisfy that then you've got a simpler form for the radical expression.
 
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Ah, ok. So there would be many other solutions, and they are only finding one such solution?
 
BMW said:
Ah, ok. So there would be many other solutions, and they are only finding one such solution?

Right. There are many other solutions. They are just looking for a nice simple one.
 
Dick said:
Right. There are many other solutions. They are just looking for a nice simple one.

So you would also be able to say that a + 2√(ab) = 6 and b = 3√2, and solve that way (with the risk of it being horribly complicated)?
 
BMW said:
So you would also be able to say that a + 2√(ab) = 6 and b = 3√2, and solve that way (with the risk of it being horribly complicated)?

Yes, there are lots of ugly solutions.
 
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