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.


Solve for x in the following equation.

Example 2:tex2html_wrap_inline155tex2html_wrap_inline130


The first step is to isolate the expression tex2html_wrap_inline132


Add 17 to both sides of the equation.


eqnarray28



Divide both sides of the equation by 3.


eqnarray34



Take the natural logarithm of both sides of the equation tex2html_wrap_inline138


eqnarray44


eqnarray47


eqnarray50


eqnarray56



The exact answer is tex2html_wrap_inline140 and the approximate answer is tex2html_wrap_inline142


When solving the above problem, you could have used any logarithm. For example, let's solve it using the logarithm with base 10.


eqnarray66


eqnarray69


eqnarray72


eqnarray80



Check this answer in the original equation.



Check the solution tex2html_wrap_inline148 by substituting tex2html_wrap_inline150 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 5.18260619449 for x, then x=5.18260619449 is a solution.


You can also check your answer by graphing tex2html_wrap_inline160 (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 5.18260619449. This means that 5.18260619449 is the real solution.








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