Concept

Extraneous Solution to a Logarithmic Equation

An extraneous solution to a logarithmic equation is a value obtained during the algebraic solving process that does not satisfy the original equation because it violates the domain restrictions of logarithms. Specifically, for a logarithmic function y=logaxy = \log_a x, the argument xx must be strictly positive (x>0x > 0), and the base aa must be positive and not equal to one (a>0a > 0 and aeq1a eq 1). When solving equations, the algebraic manipulation (such as converting to exponential form) may produce candidate solutions that would result in an invalid argument or base in the original logarithm. These mathematically invalid values must be discarded. Just as with radical equations, it is essential to check all potential solutions by substituting them back into the original logarithmic equation to identify and eliminate any extraneous solutions.

0

1

Updated 2026-05-25

Contributors are:

Who are from:

Tags

OpenStax

Intermediate Algebra @ OpenStax

Ch.10 Exponential and Logarithmic Functions - Intermediate Algebra @ OpenStax

Algebra

Related