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

Question

Complete the following exercise:

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

Video Solution

Solution Steps

00:00 Solve the following problem
00:05 A "regular" root is of the order 2
00:13 When there is a root of order (C) for root (B)
00:16 The result equals the root of the product of the orders
00:20 We will apply this formula to our exercise
00:37 When we have a root of order (C) on a number (A) to the power of (B)
00:40 The result equals number (A) to the power of (B divided by C)
00:43 We will apply this formula to our exercise, every number is to the power of 1
00:53 When we have a multiplication between powers with equal bases
00:57 The result equals the base with power equal to the sum of the powers
01:00 We will apply this formula to our exercise
01:12 We will combine the powers by finding the common denominator
01:22 A power of one-half equals a square root
01:31 We will break down 64 to 8 squared
01:34 This is the solution

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).

Answer

8