SOLVING EXPONENTIAL EQUATIONS


Note:

If you would like an in-depth review of exponents, the rules of exponents, exponential functions and exponential equations, click on exponential function. under Algebra.

Solve for x in the following equation.

Example 2:tex2html_wrap_inline155 tex2html_wrap_inline123

Isolate the exponential term.

Divide both sides of the equation by 12


eqnarray27


displaymath121



Take the natural logarithm of both sides of the equation tex2html_wrap_inline125


eqnarray38


eqnarray41


eqnarray44


eqnarray46



The exact answer is tex2html_wrap_inline127 and the approximate answer is tex2html_wrap_inline129



Your exact answer may differ dependent how what logarithm you used to solve the problem. However, all forms of the correct answer will simplify to the same approximate answer.


When solving the above problem, you could have used any logarithm. For example, let's solve it using the logarithmic with base 11.


eqnarray51


eqnarray54


eqnarray61


eqnarray67


eqnarray73


eqnarray83


eqnarray89



Check this answer in the original equation.



Check the solution tex2html_wrap_inline137 ) by substituting -5.61370563888 in the original equation for x. If the left side of the equation equals the right side of the equation after the substitution, you have found the correct answer.


Since the left side of the original equation is equal to the right side of the original equation after we substitute the value -5.61370563888 for x, then x=-5.61370563888 is a solution.


You can also check your answer by graphing tex2html_wrap_inline149 (formed by subtracting the right side of the original equation from the left side). Look to see where the graph crosses the x-axis; that will be the real solution. Note that the graph crosses the x-axis at -5.61370563888. This means that -5.61370563888 is the real solution.








If you would like to work another example, click on Example


If you would like to test yourself by working some problems similar to this example, click on Problem


If you would like to go back to the equation table of contents, click on Contents.



This site was built to accommodate the needs of students. The topics and problems are what students ask for. We ask students to help in the editing so that future viewers will access a cleaner site. If you feel that some of the material in this section is ambiguous or needs more clarification, please let us know by e-mail.


[Algebra] [Trigonometry]
[Geometry] [Differential Equations]
[Calculus] [Complex Variables] [Matrix Algebra]

S.O.S. MATHematics home page


Author:

Copyright © 1999-2004 MathMedics, LLC. All rights reserved.
Math Medics, LLC. - P.O. Box 12395 - El Paso TX 79913 - USA