If you would like an in-depth review of exponents, the rules of exponents,
exponential functions and exponential equations, click on
exponential function.
Note:
Solve for x in the following equation.
Problem 7.5b:
Answer: The exact solution is and the approximate solution is
x=-0.330482023722.
Solution:
The exponential term is already isolated.
Take the natural logarithm of both sides of the equation
The exact answer is and the approximate
answer is
When solving the above problem, you could have used any logarithm. For
example, let's solve it using the logarithm with base 37.
Check this answer in the original equation.
Check the solution by substituting -0.330482023722 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.
You can also check your answer by graphing (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 -0.330482023722
. This means that -0.330482023722 is the real solution.
If you would like to review the answer and solution to problem 7.5c, click on problem.
If you would like to go back to the equation table of contents, click on contents.
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