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

00:09 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 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