Problem 93 - College Algebra

Question

Evaluate or simplify each expression without using a calculator. $$ e^{\ln 125} $$

Step-by-Step Solution

Answer

The simplified form of \(e^{\ln 125}\) is 125.

Step 1: Understand the relationship between 'e' and 'ln'

Observe that the operation \(e\) and \(ln\) are inverse operations, meaning that when they are used one after the other, they cancel out each other's effect entirely leading to a simplified solution. Written in mathematical terms, \(e^{\ln x} = x\).

Step 2: Apply the formula

Apply the formula from step 1 to the problem at hand. In this case, \(x\) is 125 so following the formula, the simplified result is 125.

Key Concepts

Inverse Functions

Inverse functions are a central concept in mathematics, especially when dealing with exponential and logarithmic functions. When two functions are inverses of each other, applying one function and then its inverse yields the original input.

In the context of exponential functions and natural logarithms:

• The exponential function with base 'e' is denoted as \(e^x\).
• The natural logarithm function, represented as \(\ln(x)\), is the inverse of the exponential function.

When you have \(e^{\ln(x)}\), the two functions effectively cancel each other out, returning simply \(x\). This is like saying 'Do something and then undo it'—you end up where you started.
Understanding inverse functions helps simplify complex expressions and solve equations more easily. Recognizing these relationships is crucial in mathematics, as it provides a shortcut to computing expressions without manual calculation.

Natural Logarithms

Natural logarithms, abbreviated as \(\ln\), are logarithms to the base \(e\). Euler's number, \(e\), is approximately equal to 2.71828, and it is one of the most important constants in mathematics.
Here are some key points about natural logarithms:

• \(\ln(e) = 1\) because \(e^1 = e\).
• \(\ln(1) = 0\) because \(e^0 = 1\).
• \(\ln(e^x) = x\) due to the properties of logarithms which undo exponentiation.

Natural logarithms are particularly common in calculus and mathematical modeling because they arise naturally in problems involving growth processes and continuous compounding.
In expressions like \(e^{\ln(125)}\), recognizing that the logarithm and exponential operations are inverses makes it easy to simplify. Overall, natural logarithms help reveal multiplicative relationships and grow intuitions in more complex calculus concepts.

Simplifying Expressions

Simplifying expressions is the process of reducing them to their simplest form. This typically involves using algebraic rules and property of operations to make expressions as compact as possible.
When simplifying expressions involving exponentials and logarithms:

• Utilize inverse operations: if you have \(e^{\ln(x)}\), recognize that this simplifies to \(x\) immediately.
• Apply logarithmic identities, such as \(\ln(ab) = \ln(a) + \ln(b)\) or \(\ln(a^b) = b\ln(a)\).
• Focus on properties of exponents, like \(x^{a} \cdot x^{b} = x^{a+b}\).

By recognizing keys patterns, inverse relationships, and properties, anyone can simplify complex-looking equations into something more manageable. Number relationships become clearer, facilitating further calculation or integration into larger mathematical frameworks.
Simplifying is an essential skill that will allow smoother problem-solving and lays a strong foundation for advanced mathematical reasoning.