Chapter 4: Problem 15
Evaluate: a. \(27^{2 / 3}\) b. \(16^{-3 / 4}\) c. \(25^{-3 / 2}\) d. \(81^{-34}\)
Short Answer
Expert verified
a. 9, b. \frac{1}{8}, c. \frac{1}{125}, d. \frac{1}{81^{34}} or practical 0.
Step by step solution
01
Simplify the first expression
Evaluate the expression **a.** \(27^{2/3}\)The base of 27 can be written as \(3^3\), thus we can simplify:\(27^{2/3} = (3^3)^{2/3}\)Using the power of a power property \((a^m)^n = a^{m \times n}\):\((3^3)^{2/3} = 3^{3 \times \frac{2}{3}} = 3^2 = 9\)
02
Simplify the second expression
Evaluate the expression **b.** \(16^{-3/4}\)16 can be written as \(2^4\), thus we can simplify:\(16^{-3/4} = (2^4)^{-3/4}\)Using the power of a power property and negative exponent property \((a^m)^{-n} = a^{-mn}\):\((2^4)^{-3/4} = 2^{4 \times -\frac{3}{4}} = 2^{-3} = \frac{1}{2^3} = \frac{1}{8}\)
03
Simplify the third expression
Evaluate the expression **c.** \(25^{-3/2}\)The base of 25 can be written as \(5^2\), thus we can simplify:\(25^{-3/2} = (5^2)^{-3/2}\)Using the power of a power property and negative exponent property:\((5^2)^{-3/2} = 5^{2 \times -\frac{3}{2}} = 5^{-3} = \frac{1}{5^3} = \frac{1}{125}\)
04
Simplify the fourth expression
Evaluate the expression **d.** \(81^{-34}\)Using the property of integer exponents, any number to the power of zero is 1:\(81^{-34} = (81^{34})^{-1} = \frac{1}{81^{34}}\).Since the exact value is too large to express here, we summarize as \(81^{-34}\) approaches zero (or practically equivalent to zero).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Power of a Power Property
The **power of a power** property is a fundamental rule in exponentiation. It states that when an exponent is raised to another exponent, you multiply the exponents together. For example, \( (a^m)^n = a^{m \times n} \). This property simplifies complex expressions and makes calculations easier. Let's apply it:
For the expression \( 27^{2/3} \):
For the expression \( 27^{2/3} \):
- First, express 27 as \( 3^3 \).
- Then, using the power of a power property, \( (3^3)^{2/3} = 3^{3 \times 2/3} = 3^2 \).
- This simplifies to \( 9 \).
Negative Exponents
Negative exponents might seem confusing at first, but they simplify expressions greatly. A **negative exponent** indicates that the base should be taken as a reciprocal. The rule can be written as \[ a^{-n} = \frac{1}{a^n} \]. Let's look at an example:
For the expression \( 16^{-3/4} \):
For the expression \( 16^{-3/4} \):
- First, express 16 as \( 2^4 \).
- Using the power of a power property, write \( (2^4)^{-3/4} = 2^{4 \times -3/4} = 2^{-3} \).
- Then apply the negative exponent rule: \( 2^{-3} = \frac{1}{2^3} \).
- This simplifies to \( \frac{1}{8} \).
Simplifying Expressions
Simplifying expressions involves breaking them down to their simplest form using exponent rules. Knowing the properties of exponents, including **power of a power** and **negative exponents**, is essential. Let’s go through an example:
For the expression \( 25^{-3/2} \):
For the expression \( 81^{-34} \):
For the expression \( 25^{-3/2} \):
- Express 25 as \( 5^2 \).
- Using the power of a power property, write \( (5^2)^{-3/2} = 5^{2 \times -3/2} = 5^{-3} \).
- Apply the negative exponent rule: \( 5^{-3} = \frac{1}{5^3} \).
- This simplifies to \( \frac{1}{125} \).
For the expression \( 81^{-34} \):
- By applying the negative exponent rule: \( 81^{-34} = \frac{1}{81^{34}} \).
- Since \( 81^{34} \) is an incredibly large number, the value of \( \frac{1}{81^{34}} \) is practically close to zero.