Solve the Nested Radical: Cube Root of Square Root of 64

Nested Radicals with Exponent Properties

Solve the following exercise:

643= \sqrt[3]{\sqrt{64}}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve the following problem
00:03 A "regular" root is of the order 2
00:09 When we have a number (A) in a root of the order (B) in a root of the order (C)
00:14 The result equals the number (A) in a root of the order of their product (B times C)
00:18 We will apply this formula to our exercise
00:23 Let's calculate the order of multiplication
00:30 When we have a number (A) to the power of (B) in a root of the order (C)
00:36 The result equals the number (A) to the power of their quotient (B divided by C)
00:39 We will apply this formula to our exercise
00:46 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following exercise:

643= \sqrt[3]{\sqrt{64}}=

2

Step-by-step solution

To solve this problem, we'll express the nested roots using exponents and then simplify:

We start with the inner expression:

64\sqrt{64} is equivalent to 641/264^{1/2}.

Next, apply the cube root:

641/23\sqrt[3]{64^{1/2}} is equivalent to (641/2)1/3(64^{1/2})^{1/3}.

Using properties of exponents, we simplify the expression:

(641/2)1/3=64(1/2)(1/3)=641/6(64^{1/2})^{1/3} = 64^{(1/2) \cdot (1/3)} = 64^{1/6}.

Now, evaluate 641/664^{1/6}:

Since 64=2664 = 2^6, we have:

641/6=(26)1/6=26(1/6)=21=264^{1/6} = (2^6)^{1/6} = 2^{6 \cdot (1/6)} = 2^{1} = 2.

Therefore, the solution to the exercise 643 \sqrt[3]{\sqrt{64}} is 2\mathbf{2}.

3

Final Answer

2

Key Points to Remember

Essential concepts to master this topic
  • Rule: Convert nested radicals to exponential form before simplifying
  • Technique: 643=(641/2)1/3=641/6 \sqrt[3]{\sqrt{64}} = (64^{1/2})^{1/3} = 64^{1/6}
  • Check: Verify 26=64 2^6 = 64 , so 641/6=2 64^{1/6} = 2

Common Mistakes

Avoid these frequent errors
  • Evaluating radicals separately without using exponent laws
    Don't calculate 64=8 \sqrt{64} = 8 then 83=2 \sqrt[3]{8} = 2 = correct but inefficient! This approach works here but fails with complex nested radicals. Always convert to exponential form using (am)n=amn (a^m)^n = a^{mn} for systematic solutions.

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( \sqrt[10]{\sqrt[10]{1}}= \)

FAQ

Everything you need to know about this question

Why can't I just work from the inside out like normal?

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You can work inside-out for simple cases like this one! 64=8 \sqrt{64} = 8 , then 83=2 \sqrt[3]{8} = 2 . But using exponential form is more reliable for complex nested radicals and teaches you the underlying pattern.

How do I remember the exponent rule for nested radicals?

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Think of it as "multiply the exponents": x3=x1/21/3=x1/6 \sqrt[3]{\sqrt{x}} = x^{1/2 \cdot 1/3} = x^{1/6} . The outer exponent gets multiplied by the inner exponent!

What does 64^(1/6) actually mean?

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641/6 64^{1/6} means "what number raised to the 6th power equals 64?" Since 26=64 2^6 = 64 , the answer is 2. It's the 6th root of 64!

Can I use this method with any nested radical?

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Yes! Convert each radical to exponential form: xn=x1/n \sqrt[n]{x} = x^{1/n} . Then use (am)n=amn (a^m)^n = a^{mn} to multiply exponents. This works for any level of nesting!

Why is 64 written as 2^6?

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Recognizing perfect powers makes calculations easier! 64=26 64 = 2^6 because 2×2×2×2×2×2=64 2 \times 2 \times 2 \times 2 \times 2 \times 2 = 64 . This lets us simplify 641/6=(26)1/6=21=2 64^{1/6} = (2^6)^{1/6} = 2^1 = 2 easily.

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