How do I simplify radical equations with nested radicals?

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Discussion Overview

The discussion revolves around the simplification of a radical equation involving nested radicals, specifically the expression sqrt(11+sqrt(72)) + sqrt(11-sqrt(72)). Participants explore various approaches to simplify this expression and verify the result.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant presents the expression to simplify and mentions that a calculator suggests the answer is 6.
  • Another participant suggests letting x be the surd and squaring it to find a solution.
  • A subsequent post questions the terminology used, specifically the term "surd."
  • A detailed step-by-step approach is provided by a participant, who sets the expression equal to x, squares both sides, and simplifies to arrive at x=6.
  • Another participant confirms the use of the term "surd" and reiterates the simplification process, concluding that the result is 6 with the appropriate choice of sign.

Areas of Agreement / Disagreement

Participants generally agree on the process of squaring the expression and simplifying it, leading to the result of 6. However, there is no explicit consensus on the terminology used, as one participant questions the term "surd."

Contextual Notes

The discussion does not address potential limitations or assumptions in the simplification process, nor does it explore any alternative methods for solving the problem.

Who May Find This Useful

Students or individuals interested in learning about the simplification of radical expressions, particularly those involving nested radicals.

Agent_J
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Simplify
sqrt(11+sqrt72)) + sqrt(11-sqrt(72))

better picture here
http://members.rogers.com/agentj/images/math.jpg

I don't know where to begin for this one, but apparently my calculator says the answer is 6 :redface:
 
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let x be the surd, square x, what do you get?
 
let x be the "surd"?
 
ok, set sqrt(11+sqrt72)) + sqrt(11-sqrt(72)) = x
(by the way, sqrt(72) = 6*sqrt(2), which i'll just call 6r2 for simplicity)
square both sides, we get
(sqrt(11+sqrt72)) + sqrt(11-sqrt(72)))^2 = x^2
simplify and you get
11+6r2+2*sqrt((11+6r2)(11-6r2))+11-6r2=x^2
22+2sqrt(121+11*6r2-11*6r2-36*2)=x^2
22+2*sqrt(121-72)=x^2
22+2*sqrt(49)=x^2
22+2*7=x^2
36=x^2
x=6 (well, plus or minus, but we know it must be positive since the addition of two non-complex roots must be >= 0)
 
Yes, surd: an expression involving radicals. I just didn't want to have to type it out. Just square the expression, simplify and take the square root, et voila, we have 6, with the appropriate choice of sign.
 

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