Chapter 3: Problem 7
Evaluate (a) \(4^{1 / 2}\) (b) \(16^{3 / 4}\) (c) \(27^{2 / 3}\) (d) \(9^{-1 / 2}\)
Short Answer
Expert verified
(a) 2; (b) 8; (c) 9; (d) 1/3.
Step by step solution
01
Understanding Radicals in Exponent Form
To evaluate expressions like these, remember that fractional exponents represent radicals. The expression \(a^{m/n}\) can be interpreted as \(\sqrt[n]{a^m}\). This means the numerator \(m\) is a power and the denominator \(n\) is a root.
02
Evaluating (a) \(4^{1/2}\)
Start by recognizing that \(4^{1/2}\) represents the square root of 4. Thus, \(4^{1/2} = \sqrt{4}\). Calculate the square root: \(\sqrt{4} = 2\).
03
Evaluating (b) \(16^{3/4}\)
First, recognize \(16^{3/4}\) means the fourth root of 16, raised to the power of 3. Calculate the fourth root of 16 first: \(\sqrt[4]{16} = 2\), since \(2^4 = 16\). Then raise 2 to the power of 3: \(2^3 = 8\). Therefore, \(16^{3/4} = 8\).
04
Evaluating (c) \(27^{2/3}\)
This expression means find the cube root of 27, then square the result. \(\sqrt[3]{27} = 3\) because \(3^3 = 27\). Then square this result: \(3^2 = 9\). Hence, \(27^{2/3} = 9\).
05
Evaluating (d) \(9^{-1/2}\)
Here, \(9^{-1/2}\) indicates the reciprocal of the square root of 9. Calculate the square root: \(\sqrt{9} = 3\). Therefore, the reciprocal is \(1/3\). Hence \(9^{-1/2} = 1/3\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radicals
Radicals are a way to represent roots in mathematics. When you see a symbol like \( \sqrt[n]{a} \), it indicates the nth root of a number \( a \). This means you are looking for a number which, when multiplied by itself \( n \) times, gives you \( a \). Radicals can be used to express higher roots like cube roots, fourth roots, and so on.
- When \( n = 2 \), it is called the square root.
- When \( n = 3 \), it is called the cube root.
Square Root
The square root is a specific radical representing the number that, when multiplied by itself, results in the original number. For the expression \( a^{1/2} \), it refers to this operation.
- Example: \( \sqrt{4} = 2 \) because \( 2 \times 2 = 4 \).
- Fractional exponent form: \( 4^{1/2} = \sqrt{4} \).
Cube Root
The cube root involves finding a number which, when used three times in a multiplication, returns the original number. Equivalent fractional exponent representation is \( a^{1/3} \). This operation is crucial for simplifying expressions involving third powers.
- Example: \( \sqrt[3]{27} = 3 \) because \( 3 \times 3 \times 3 = 27 \).
- Fractional exponent form: \( 27^{1/3} = \sqrt[3]{27} \).
Reciprocal
The concept of a reciprocal is fundamental in understanding negative exponents. The reciprocal of a number is simply \( 1 \) divided by that number. For instance, the reciprocal of \( 3 \) is \( 1/3 \).
- When dealing with negative exponents, like \( 9^{-1/2} \), it implies the operation involves a reciprocal.
- Example: \( 9^{-1/2} = \frac{1}{\sqrt{9}} = 1/3 \).