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.


Problem 7.5c: tex2html_wrap_inline116


Answer: tex2html_wrap_inline155 The exact solution is tex2html_wrap_inline118 and the approximate solution is x = 8.54956933001.


Solution:

The exponential term is already isolated.

Take the natural logarithm of both sides of the equation tex2html_wrap_inline122


eqnarray37


eqnarray40



The exact answer is tex2html_wrap_inline124 and the approximate answer is tex2html_wrap_inline126


When solving the above problem, you could have used any logarithm. For example, let's solve it using the logarithm with base 37.


eqnarray47


eqnarray50


eqnarray57


eqnarray65



Check this answer in the original equation.

Check the solution tex2html_wrap_inline132 by substituting 8.54956933001 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 8.54956933001 for x, then x=8.54956933001 is a solution.


You can also check your answer by graphing tex2html_wrap_inline144 (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 8.54956933001. This means that 8.54956933001 is the real solution.


If you would like to review the answer and solution to problem 7.5d, click on problem.

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

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