Problem 10 - College Algebra and Calculus: An Applied Approach

Question

Solve for \(x\).\(\ln (2 x-1)=0\)

Step-by-Step Solution

Answer

The solution for \( x \) is 1

Step 1: Start with the given equation

The original equation is \( \ln (2x - 1) = 0 \)

Step 2: Use logarithmic property

It is known that \( \ln(a) = 0 \) if and only if \( a=1 \). With this principle, equate the term that the logarithm acts on to 1. That gives the equation \( 2x - 1 = 1 \)

Step 3: Solve for \( x \)

To solve for \( x \), first add 1 to both sides of the equation to balance it. That gives \( 2x = 2 \). Next, divide both sides of the equation by 2 to solve for \( x \) which gives \( x = 1 \)

Key Concepts

Natural Logarithm Properties

The natural logarithm, denoted as \( \ln(x) \) and alternatively known as the Napierian logarithm, has a base of \( e \)—Euler's number, which is approximately 2.71828. This special logarithm comes with its unique set of properties that are vital for solving logarithmic equations.

One fundamental property used often is that \( \ln(1) = 0 \) since any number raised to the power of 0 is 1, and \( e^0 = 1 \). Another key property is the inverse nature of exponential and logarithmic functions; for \( x > 0 \), \( \ln(e^x) = x \) and \( e^{\ln(x)} = x \). This relationship is essential when unraveling logarithmic equations.

Understanding these properties empowers students to solve logarithmic equations efficiently by recognizing patterns and applying the correct operations to isolate the variable.

Logarithmic Equation Steps

Solving logarithmic equations typically involves a sequence of steps that systematically unfold the solution. Here's a breakdown of those steps, tailored to our example \( \ln(2x - 1) = 0 \):

1. Identify the logarithmic term.
2. Apply logarithmic properties, such as \( \ln(a) = 0 \) implies \( a = 1 \), to rewrite the equation in an equivalent, but simpler, form.
3. Perform algebraic manipulations to solve for the variable. This often includes operations such as addition, subtraction, multiplication, division, and sometimes even using properties of exponents when the equation is more complex.

By following these structured steps, students can simplify the process of solving logarithmic equations and reduce the risk of errors.

Algebraic Manipulation

Algebraic manipulation is a critical skill in mathematics, as it involves rearranging equations and expressions using arithmetic operations and algebraic properties to solve for variables or simplify expressions.

In the context of logarithmic equations, such as our exercise \( \ln(2x - 1) = 0 \), algebraic manipulation comes into play after applying logarithmic properties. Students are expected to:

• Isolate the terms involving the variable,
• Combine like terms,
• Use inverse operations to get the variable on one side of the equation,
• And finally, simplify to find the solution.

The judicious application of these algebraic techniques is essential not only for finding the correct solution but also for developing a solid understanding of the underlying mathematical principles.