Chapter 4: Problem 25
Evaluate the expression. (a) \(2^{\log _{2} 37}\) (b) \(3^{\log _{3} 8}\) (c) \(e^{\ln \sqrt{5}}\)
Short Answer
Expert verified
(a) 37, (b) 8, (c) \( \sqrt{5} \)
Step by step solution
01
Understand the Exponent Logarithm Rule
The general rule to solve expressions of the type \( a^{\log_{a}(b)} \) is that it simplifies directly to \( b \). This is because the logarithm function \( \log_{a}(b) \) gives the power to which \( a \) must be raised to get \( b \). Therefore, \( a^{\log_{a}(b)} = b \). This rule will be applied to both parts (a) and (b).
02
Evaluate Part (a)
For part (a), the expression is \( 2^{\log_{2}(37)} \). Applying the exponent logarithm rule, \( 2^{\log_{2}(37)} = 37 \).
03
Evaluate Part (b)
For part (b), the expression is \( 3^{\log_{3}(8)} \). Similarly applying the exponent logarithm rule, \( 3^{\log_{3}(8)} = 8 \).
04
Understand the Natural Exponential-Logarithm Identity
The expression \( e^{\ln b} \) simplifies to \( b \) for any positive \( b \). This is because \( \ln b \) is the natural logarithm of \( b \), implying that \( e^{\ln b} = b \). This applies to part (c).
05
Evaluate Part (c)
For part (c), the expression is \( e^{\ln \sqrt{5}} \). By the exponential-logarithm identity, it simplifies directly to \( \sqrt{5} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponent Logarithm Rule
The Exponent Logarithm Rule is a fundamental concept in exponential and logarithmic functions, simplifying expressions of the form \( a^{\log_{a}(b)} \). In simple terms, the expression resolves to \( b \). This is because the logarithmic function \( \log_{a}(b) \) determines the power needed for the base \( a \) to produce \( b \). So, raising \( a \) to the power of \( \log_{a}(b) \) precisely concludes with \( b \). For example:
- If you have \( 2^{\log_{2}(37)} \), the base and the logarithm base match, simplifying directly to 37.
- Similarly, \( 3^{\log_{3}(8)} \) simplifies to 8.
Natural Logarithm
The natural logarithm, denoted as \( \ln \), is a specific logarithm that uses the base \( e \), where \( e \approx 2.71828 \). This irrational number \( e \) is essential in mathematics, often appearing in growth and decay scenarios, such as population growth and radioactive decay. It forms the foundation for natural exponential functions.
When you encounter \( e^{\ln b} \), it directly simplifies to \( b \). This simplification is due to the identity rule in natural logarithms, as \( \ln b \) is the power of \( e \) needed to achieve \( b \). For example:
When you encounter \( e^{\ln b} \), it directly simplifies to \( b \). This simplification is due to the identity rule in natural logarithms, as \( \ln b \) is the power of \( e \) needed to achieve \( b \). For example:
- If you have \( e^{\ln \sqrt{5}} \), the expression simplifies directly to \( \sqrt{5} \).
Properties of Exponents
Properties of exponents are shorthand rules designed to simplify and manage expressions involving powers. These properties are essential in algebra, calculus, and beyond. Here's a brief insight into some key properties:
- Product of Powers Property: \( a^m \times a^n = a^{m+n} \). You add the exponents when multiplying like bases.
- Quotient of Powers Property: \( \frac{a^m}{a^n} = a^{m-n} \) evaluates a division by subtracting exponents.
- Power of a Power Property: \( (a^m)^n = a^{m \times n} \) handles nested exponents by multiplying them.
- Zero Exponent Rule: \( a^0 = 1 \) for any \( a eq 0 \). This rule signals that any base to the zero power equals one.