If you would like an in-depth review of logarithms, the rules of logarithms, logarithmic functions and logarithmic equations, click on logarithmic function.
Solve for x in the following equation.
Note that the domain of is the set of real numbers greater than zero because you cannot take the log of zero or a negative number.
The exact value is and the approximate value
Check the solution by substituting 20.085537 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 20.085537. This means that 20.085537 is the real solution.
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.
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