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 7.3d

tex2html_wrap_inline159

Answer:No solution.


Solution:


Note that the domain is the set of real numbers such that tex2html_wrap_inline161 or tex2html_wrap_inline163


Isolate the exponential term in the equation tex2html_wrap_inline159 .


Divide both sides of the equation by 56


eqnarray41


eqnarray46





Square both sides of the equation. tex2html_wrap_inline169


eqnarray64


eqnarray72





Take the natural log of both sides of the equation tex2html_wrap_inline171


eqnarray91


eqnarray97


eqnarray104


eqnarray106



Since 0.74247042592 is not tex2html_wrap_inline175 , there is not solution.





You can also check your answer by graphing tex2html_wrap_inline177 (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 never crosses the x-axis.. This means that there are no real solutions.




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Author: Nancy Marcus

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