How do I simplify radical equations with nested radicals?

In summary, the expression sqrt(11+sqrt72)) + sqrt(11-sqrt(72)) simplifies to 6 when squared, simplified, and square rooted. This can be done by setting the expression equal to x and following the steps of squaring, simplifying, and square rooting. The result is 6, with the appropriate choice of sign.
  • #1
Agent_J
13
0
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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  • #2
let x be the surd, square x, what do you get?
 
  • #3
let x be the "surd"?
 
  • #4
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)
 
  • #5
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.
 

Related to How do I simplify radical equations with nested radicals?

1. What is a radical equation?

A radical equation is an equation that contains a radical expression, such as a square root, cube root, or higher root. It also typically includes variables and numerical constants.

2. How do I simplify a radical equation?

To simplify a radical equation, you must first isolate the radical expression on one side of the equation. Then, you can use properties of radicals, such as the product and quotient rules, to simplify the expression. Finally, solve for the variable in the simplified equation.

3. Can a radical equation have extraneous solutions?

Yes, a radical equation can have extraneous solutions, which are values that do not satisfy the original equation but are obtained during the simplification process. It is important to check for extraneous solutions when solving radical equations.

4. Are there any restrictions when simplifying radical equations?

Yes, there are restrictions when simplifying radical equations. For example, the radicand (the number under the radical symbol) cannot be negative when simplifying square roots. Additionally, any variables under the radical must have even exponents.

5. What are some tips for simplifying radical equations?

Some tips for simplifying radical equations include: removing perfect square factors from the radicand, using the product and quotient rules, rationalizing the denominator if necessary, and checking for extraneous solutions. It is also helpful to practice and become familiar with common radical expressions and their simplifications.

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