Chapter 7: Problem 57
Simplify. \(\sqrt[3]{128}\)
Short Answer
Expert verified
4 \(\root[3]{2}\)
Step by step solution
01
Prime Factorization
The first step in simplifying \(\root[3]{128}\) is to perform the prime factorization of 128. Start by dividing 128 by 2 (the smallest prime number) to get 64. Continue dividing by 2: \(128 = 2 \times 64\), \(64 = 2 \times 32\), \(32 = 2 \times 16\), \(16 = 2 \times 8\), \(8 = 2 \times 4\), \(4 = 2 \times 2\). Thus, 128 can be written as \128 = 2^7\.
02
Use Cube Root Property
Next, use the cube root property on the prime factorization result. Recall that \(\root[3]{a^3} = a\). We have: \(\root[3]{128} = \root[3]{2^7}\).
03
Simplify Using Properties of Exponents
Separate the exponents in a form that includes cubes. Since \2^7\ can be separated into \2^6 \times 2\, rewrite \(\root[3]{2^7} = \root[3]{2^6 \times 2} = \root[3]{(2^2)^3 \times 2} \).
04
Simplify the Expression
Simplify the expression using cube root properties: \(\root[3]{(2^2)^3 \times 2} = \root[3]{(2^2)^3} \times \root[3]{2} = 2^2 \times \root[3]{2} = 4 \times \root[3]{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Prime Factorization
Prime factorization is the process of breaking down a number into its prime components. Prime numbers are numbers greater than 1 that have no divisors other than 1 and themselves. For example, when simplifying \(\root[3]{128}\), we start by finding its prime factors.
We divide 128 by the smallest prime number, 2, which results in 64. We keep dividing by 2 until we get to the prime factors:
We divide 128 by the smallest prime number, 2, which results in 64. We keep dividing by 2 until we get to the prime factors:
- 128 ÷ 2 = 64
- 64 ÷ 2 = 32
- 32 ÷ 2 = 16
- 16 ÷ 2 = 8
- 8 ÷ 2 = 4
- 4 ÷ 2 = 2
- 2 ÷ 2 = 1
Properties of Exponents
Understanding the properties of exponents makes simplifying expressions more manageable. Here are a few essential properties:
- Product of Powers: \(a^m \times a^n = a^{m+n}\)
- Power of a Power: \((a^m)^n = a^{m \times n}\)
- Power of a Product: \((ab)^n = a^n \times b^n\)
Cube Root Property
The cube root property states \(\root[3]{a^3} = a\). This property helps in simplifying radical expressions.
In our example, we use it on the prime factorized expression of 128, which is \(2^7\). Rewriting \(2^7\) as \((2^2)^3 \times 2\), we can separate and simplify the cube root:
\[\root[3]{(2^2)^3 \times 2} = \root[3]{(2^2)^3} \times \root[3]{2} = 2^2 \times \root[3]{2} = 4 \times \root[3]{2} \]
Hence, the simplified form of \(\root[3]{128}\) is \(4 \times \root[3]{2}\).
In our example, we use it on the prime factorized expression of 128, which is \(2^7\). Rewriting \(2^7\) as \((2^2)^3 \times 2\), we can separate and simplify the cube root:
\[\root[3]{(2^2)^3 \times 2} = \root[3]{(2^2)^3} \times \root[3]{2} = 2^2 \times \root[3]{2} = 4 \times \root[3]{2} \]
Hence, the simplified form of \(\root[3]{128}\) is \(4 \times \root[3]{2}\).