Problem 74 - Algebra 2

Question

Simplify each expression. \(\ln e^{3}\)

Step-by-Step Solution

Answer

The simplified form of the expression \(\ln e^{3}\) is 3.

Step 1: Identify the natural logarithm and its properties

The natural logarithm \(\ln(x)\) and the exponential \(e^{x}\) are inverse functions of each other. That means when they are combined, their operations cancel out and the answer must be the exponent itself.

Step 2: Simplify the expression

Looking at the expression \(\ln e^{3}\), the base of the logarithm and the base of the exponent is \(e\). Applying the principle from Step 1, that when combined, they cancel out to produce the exponent, the simplification results in the number 3.

Key Concepts

Inverse Functions

Inverse functions are pairs of functions that, when composed together, give the identity function. This means they essentially "undo" each other. The natural logarithm function \( \ln(x) \) and the exponential function \( e^x \) are classic examples of inverse functions. When you apply a function to a value and then its inverse function, you return to the original value. For instance:

• If you start with a number \( x \), apply the natural logarithm \( \ln(x) \), and then exponentiate the result back using base \( e \), you get \( x \) back: \( e^{\ln(x)} = x \).
• Similarly, if you exponentiate \( x \) with base \( e \), then take the natural logarithm of the result, you again return to \( x \): \( \ln(e^x) = x \).

In our given problem \( \ln e^{3} \), since \( \ln \) and \( e^x \) are inverse functions, their operations cancel each other out, leaving us with the exponent, which is 3.

Exponentiation

Exponentiation is a mathematical operation involving two numbers, the base and the exponent or power. When you raise a base to an exponent, you multiply the base by itself as many times as the exponent indicates. For example, \( e^3 \) means multiplying \( e \) by itself three times.

• \( e^3 = e \times e \times e \)

Every exponential function has a base, and one of the most common bases in mathematics is \( e \), approximately equal to 2.71828. The function \( e^x \) plays a pivotal role in calculus and mathematical modeling because of its unique properties of growth and decay.In the original problem, we see the expression \( e^3 \). This step of exponentiation is made even more interesting because exponentials are the natural logarithm's inverse. That's why, in the backward process of reversing \( e^3 \) with \( \ln \), we simply recover the exponent, demonstrating the power and simplicity of inverse functions in arithmetic.

Logarithmic Properties

Logarithms have several properties that make them incredibly useful in mathematics. The natural logarithm, denoted as \( \ln(x) \), has a base \( e \) and is used frequently alongside exponential functions. These two are tightly interconnected due to their inverse relationship.

• Product Property: \( \ln(xy) = \ln(x) + \ln(y) \).
• Quotient Property: \( \ln\left(\frac{x}{y}\right) = \ln(x) - \ln(y) \).
• Power Property: \( \ln(x^n) = n\ln(x) \).
• Inverse Property: \( \ln(e^x) = x \)

The inverse property is especially important in our context since it highlights the role of the natural logarithm in simplifying expressions involving exponential functions. For instance, \( \ln(e^3) = 3 \). This shows how the logarithm "brings down" the exponent, honoring the agreement between logarithms and exponents for simplified calculations.