Chapter 4: Problem 16
Evaluate the expression by hand. $$ \left(2^{-2}\right)^{-3 / 2} $$
Short Answer
Expert verified
The evaluated expression is 8.
Step by step solution
01
Simplify the Inner Exponent
Start by simplifying the inner expression, which is \( 2^{-2} \). Recall the rule of exponents \( a^{-n} = \frac{1}{a^n} \). Thus, \( 2^{-2} = \frac{1}{2^2} = \frac{1}{4} \).
02
Apply the Outer Exponent
Next, we apply the outer exponent \( -\frac{3}{2} \) to the simplified form of \( 2^{-2} \). Hence, it becomes:\[ \left( \frac{1}{4} \right)^{-3/2} \]. According to exponent rules, \( (a^m)^n = a^{m \cdot n} \), this becomes \( 4^{3/2} \).
03
Evaluate the Exponentiation
To compute \( 4^{3/2} \), rewrite the expression as \((2^2)^{3/2}\). Using exponent rules: \((a^m)^n = a^{m \cdot n}\), we get \(2^{2 \cdot \frac{3}{2}} = 2^3\). Hence, \( 2^3 = 8 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponent Rules
Exponents are a shorthand way to express repeated multiplication of the same number. For example, \( a^n \) means "\( a \) multiplied by itself \( n \) times." There are several key rules for working with exponents that are vital for simplifying expressions correctly.
Here are some of the most important exponent rules:
Here are some of the most important exponent rules:
- Multiplication Rule: When multiplying two exponents with the same base, add the exponents: \( a^m \times a^n = a^{m+n} \).
- Division Rule: When dividing two exponents with the same base, subtract the exponents: \( \frac{a^m}{a^n} = a^{m-n} \).
- Power of a Power Rule: When raising an exponent to another power, multiply the exponents: \( (a^m)^n = a^{m \cdot n} \).
- Negative Exponent Rule: A negative exponent represents the reciprocal of the base raised to the opposite positive exponent: \( a^{-n} = \frac{1}{a^n} \).
Simplifying Expressions
Simplifying mathematical expressions with exponents involves applying the appropriate exponent rules to reduce the complexity of the expression while maintaining its equivalence.
Let's look at the original exercise: \( \left(2^{-2}\right)^{-3/2} \).
**Step-by-Step Simplification**
Let's look at the original exercise: \( \left(2^{-2}\right)^{-3/2} \).
**Step-by-Step Simplification**
- First Step: Begin with the innermost expression, \( 2^{-2} \). Using the negative exponent rule, rewrite it as \( \frac{1}{2^2} \).
- Second Step: Simplify by calculating \( \frac{1}{2^2} = \frac{1}{4} \).
- Third Step: Take the result, \( \frac{1}{4} \), and apply the outer exponent \( -\frac{3}{2} \). This transforms the expression into \( \left(\frac{1}{4}\right)^{-3/2} \).
- Fourth Step: Using the power of a power rule, this step becomes \( 4^{3/2} \).
- Fifth Step: Convert \( 4^{3/2} \) as \((2^2)^{3/2} \) to utilize easier calculation with a base of 2, solving \( 2^3 = 8 \).
Negative Exponents
Negative exponents might look intimidating at first, but they simply indicate the reciprocal of a number raised to a positive exponent. It's essential to tackle negative exponents correctly to simplify expressions accurately.
For example, the expression \( a^{-n} \) can be rewritten as \( \frac{1}{a^n} \). This transformation makes it easier to handle calculations.
Consider the exercise again: \( 2^{-2} \) becomes \( \frac{1}{2^2} = \frac{1}{4} \). Negative exponents are not only used to simplify expressions but also bridge connections to other exponent rules, such as when combining or raising power to a power.
It’s critical to remember that:
For example, the expression \( a^{-n} \) can be rewritten as \( \frac{1}{a^n} \). This transformation makes it easier to handle calculations.
Consider the exercise again: \( 2^{-2} \) becomes \( \frac{1}{2^2} = \frac{1}{4} \). Negative exponents are not only used to simplify expressions but also bridge connections to other exponent rules, such as when combining or raising power to a power.
It’s critical to remember that:
- Negative exponents do not make the answer negative; they invert the base.
- Applying the reciprocal makes expressions easier to solve or further simplify.
- When both negative and positive exponents appear, address negative exponents first to eliminate their complexity.