Skip to main content
Ch. 4 - Exponential and Logarithmic Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 5, Problem 101

Write each equation in its equivalent exponential form. Then solve for x. log3 (x-1) = 2

Verified step by step guidance
1
Recall the definition of logarithm: if \( \log_b a = c \), then the equivalent exponential form is \( b^c = a \).
Apply this definition to the given equation \( \log_3 (x-1) = 2 \). Rewrite it as \( 3^2 = x - 1 \).
Calculate the exponential expression \( 3^2 \) (you can leave it as \( 3^2 \) for now if you prefer).
Set up the equation \( 3^2 = x - 1 \) and solve for \( x \) by adding 1 to both sides: \( x = 3^2 + 1 \).
Check the solution by substituting \( x \) back into the original logarithmic equation to ensure the argument \( x - 1 \) is positive and the equation holds true.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Definition of Logarithms

A logarithm answers the question: to what exponent must the base be raised to produce a given number? For example, log_b(a) = c means b^c = a. Understanding this definition is essential to rewrite logarithmic equations in exponential form.
Recommended video:
7:30
Logarithms Introduction

Converting Logarithmic Equations to Exponential Form

To solve logarithmic equations, rewrite them in exponential form using the equivalence log_b(a) = c ⇔ b^c = a. This conversion simplifies solving for the variable inside the logarithm by turning the equation into an exponential equation.
Recommended video:
5:02
Solving Logarithmic Equations

Solving Exponential Equations

Once the equation is in exponential form, solve for the variable by isolating it. This may involve basic algebraic operations such as addition, subtraction, multiplication, division, or taking roots, depending on the equation's complexity.
Recommended video:
5:47
Solving Exponential Equations Using Logs