Simplify the Expression: Cube Root of Square Root of 64 × Cube Root of 64

Radical Operations with Nested Roots

Complete the following exercise:

643643= \sqrt[3]{\sqrt{64}}\cdot\sqrt[3]{64}=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:09 Let's solve this problem together.
00:14 A regular square root is the same as saying the order of two.
00:22 When you have a root of order C, for a root of B,
00:26 the result is the root of the products of their orders.
00:30 Let's apply this calculation to our exercise.
00:46 If we have a root of order C, on a number A to the power of B,
00:50 the result is A to the power of B, divided by C.
00:55 Again, we'll use this for our exercise. Remember, every number is to the power of one.
01:02 If you multiply powers with the same base,
01:06 the result is the base raised to their powers added together.
01:10 We'll use this formula now in our exercise.
01:21 Let's combine the powers by finding a common denominator.
01:31 Remember, a power of one-half is the same as a square root.
01:40 Let's change 64 to 8 squared.
01:43 And that's how we solve this problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Complete the following exercise:

643643= \sqrt[3]{\sqrt{64}}\cdot\sqrt[3]{64}=

2

Step-by-step solution

Let's solve the problem step-by-step.

  • Step 1: Simplify 643 \sqrt[3]{\sqrt{64}} .
  • Step 2: Simplify 643 \sqrt[3]{64} .
  • Step 3: Multiply the results of Step 1 and Step 2.

Step 1: Consider 643 \sqrt[3]{\sqrt{64}} .

We can write 64 \sqrt{64} as 641/2 64^{1/2} . Thus, 643=641/23 \sqrt[3]{\sqrt{64}} = \sqrt[3]{64^{1/2}} .

Using the property amn=am/n \sqrt[n]{a^m} = a^{m/n} , we have (641/2)1/3=641/6 (64^{1/2})^{1/3} = 64^{1/6} .

Step 2: Simplify 643 \sqrt[3]{64} .

The cube root of a number b b is expressed as b1/3 b^{1/3} . Therefore, 643=641/3 \sqrt[3]{64} = 64^{1/3} .

Step 3: Multiply the two results.

We now compute 641/6641/3 64^{1/6} \cdot 64^{1/3} .

Using the property of exponents, aman=am+n a^m \cdot a^n = a^{m+n} , thus 641/6641/3=64(1/6+1/3)=64(1/6+2/6)=643/6=641/2 64^{1/6} \cdot 64^{1/3} = 64^{(1/6 + 1/3)} = 64^{(1/6 + 2/6)} = 64^{3/6} = 64^{1/2} .

Finally, 641/2 64^{1/2} is simply 64 \sqrt{64} , which equals 8 8 .

Therefore, the solution to the problem is 8 8 , which corresponds to choice (3).

3

Final Answer

8

Key Points to Remember

Essential concepts to master this topic
  • Rule: Convert nested radicals to fractional exponents for easier computation
  • Technique: 643=641/6 \sqrt[3]{\sqrt{64}} = 64^{1/6} , then multiply by 641/3 64^{1/3}
  • Check: Verify 641/2=64=8 64^{1/2} = \sqrt{64} = 8

Common Mistakes

Avoid these frequent errors
  • Computing roots separately without combining exponents
    Don't calculate 643=2 \sqrt[3]{\sqrt{64}} = 2 and 643=4 \sqrt[3]{64} = 4 then multiply = wrong answer 8! This misses the exponent combination rule. Always convert to fractional exponents first, then use aman=am+n a^m \cdot a^n = a^{m+n} .

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

\( \sqrt{\frac{2}{4}}= \)

FAQ

Everything you need to know about this question

Why do I need to use fractional exponents instead of just computing the roots?

+

Fractional exponents make it much easier to combine operations! When you have 643 \sqrt[3]{\sqrt{64}} , converting to 641/6 64^{1/6} lets you use exponent rules directly.

How do I convert nested radicals to exponents?

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Work from inside out: 64=641/2 \sqrt{64} = 64^{1/2} , then 641/23=(641/2)1/3=641/6 \sqrt[3]{64^{1/2}} = (64^{1/2})^{1/3} = 64^{1/6} . The exponents multiply when you have nested operations!

What if I get confused adding the fractions 1/6 + 1/3?

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Find a common denominator! Convert 13 \frac{1}{3} to 26 \frac{2}{6} , so 16+26=36=12 \frac{1}{6} + \frac{2}{6} = \frac{3}{6} = \frac{1}{2} .

How can I check if 64^(1/2) really equals 8?

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Remember that 641/2=64 64^{1/2} = \sqrt{64} . Since 8×8=64 8 \times 8 = 64 , we know 64=8 \sqrt{64} = 8 . Always verify by squaring your answer!

Can I use this method for other nested radicals?

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Absolutely! This fractional exponent method works for any nested radical. Just convert each radical to its fractional form and combine using exponent rules.

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