Problem 21 - Precalculus : Building Concepts and Connections

Question

Evaluate each expression without using a calculator. $$\ln e^{1 / 3}$$

Step-by-Step Solution

Answer

The result of \(\ln e^{1 / 3}\) is \(1/3\).

Step 1: Identify the Expression

We need to evaluate or simplify: \(\ln e^{1 / 3}\).

Step 2: Apply Order of Operations

Following the order of operations (PEMDAS/BODMAS), we simplify the expression step by step, handling parentheses, exponents, multiplication/division, then addition/subtraction.

Step 3: Compute the Result

Carrying out the operations systematically, we arrive at the result.

Step 4: State the Result

The result of \(\ln e^{1 / 3}\) is \(1/3\).

Key Concepts

Natural Logarithm

The natural logarithm, denoted as \(\ln\), is a special type of logarithm that has the mathematical constant \(e\) as its base. The constant \(e\) is approximately 2.71828 and is fundamental to many areas of mathematics, including calculus and complex analysis. A natural logarithm essentially answers the question: 'To what power do we have to raise \(e\) to obtain a certain number?' In formula terms, if \(\ln(x) = y\), then by definition \(e^y = x\).

This concept becomes particularly useful when dealing with exponential growth or decay, as many natural processes, such as population growth or radioactive decay, can be modeled using the base \(e\). In our exercise, simplification relies on understanding that \(\ln(e)\) is always 1, because \(e^1 = e\). Therefore, \(\ln(e^{1 / 3})\) simplifies directly to \(1/3\) because \(e\) raised to \(1/3\) yields the original value within the logarithm.

Exponential Functions

Exponential functions are mathematical expressions where a constant base is raised to a variable exponent. The general form is \(a^x\), where \(a\) is the base and \(x\) is the exponent. These functions are unique because their rate of growth is proportional to the value of the function itself. In other words, they grow faster as they get larger, making them indispensable in describing phenomena that spread or increase rapidly.

When the base of an exponential function is \(e\), the function is known as the 'natural exponential function' and is written as \(e^x\). It has a remarkable property that the slope of the curve at any point is equal to the value of the function at that point. In the context of our exercise, we're looking at the natural exponential function with \(\frac{1}{3}\) as the exponent. This might represent a scenario where something grows to a third of its potential in one time unit, according to the natural growth constant.

Logarithmic Simplification

Logarithmic simplification is the process of using logarithmic properties to make complex expressions easier to understand and solve. Key to this process is understanding the relationship between logarithms and exponents since a logarithm can be seen as the inverse operation to exponentiation.

• For example, \(\log_b(b^x) = x\) simplifies to \(x\) because base \(b\) raised to \(x\) is what the logarithm is solving for.
• Another useful property is \(\log_b(1) = 0\), which arises from the fact that any number raised to the power of zero is 1.
• \(\log_b(mn) = \log_b(m) + \log_b(n)\) shows how logarithms can break down multiplication into addition, making complex multiplication problems simpler.

Using these properties, expressions can often be rewritten in a simpler form that may be more intuitive or easier to compute, especially when calculations are performed without a calculator. In the exercise, by understanding that \(\ln\) is the logarithm with \(e\) as the base, we can quickly simplify \(\ln(e^{1 / 3})\) to \(1/3\) using the basic properties of logarithms.