If you would like an in-depth review of exponents, the rules of logarithms,
logarithmic functions and logarithmic equations, click on
If you would like an in-depth review of exponents, the rules of logarithms, logarithmic functions and logarithmic equations, click on logarithmic function.
Solve for x in the following equation.
The above equation is valid only if all of the terms are valid. The first term is valid if the second term is valid if and the third term is valid if Therefore, the equation is valid when all three of these conditions are met, or when x > 3. The domain is the set of real numbers greater than 3.
Simplify both sides of the equation using the rules of logarithms.
Recall that if then a = b. Therefore, if
Solve for x.
The exact answers are x = 4 and However, only x = 4 is in the domain.
Check the answer x = 4 by substituting 4 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 4. This means that 4 is the real solution.
If you would like to review the solution to problem 8.3c, click on problem.
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