Questions: Solve the logarithmic equation.
2 log3(4-x) - log3 5 = log3 45
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. x= (Simplify your answer. Use a comma to separate answers as needed.)
B. There is no solution.
Transcript text: Solve the logarithmic equation.
\[
2 \log _{3}(4-x)-\log _{3} 5=\log _{3} 45
\]
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. $x=$ $\square$ (Simplify your answer. Use a comma to separate answers as needed.)
B. There is no solution.
Solution
Solution Steps
To solve the given logarithmic equation, we can use the properties of logarithms to combine and simplify the terms. First, apply the power rule to the first term, then use the subtraction rule to combine the logarithms on the left side. Finally, equate the simplified expression to the right side and solve for \( x \).
Step 1: Rewrite the Equation
We start with the logarithmic equation:
\[
2 \log_{3}(4 - x) - \log_{3}(5) = \log_{3}(45)
\]
Step 2: Apply Logarithmic Properties
Using the properties of logarithms, we can rewrite the left side:
\[
\log_{3}((4 - x)^2) - \log_{3}(5) = \log_{3}(45)
\]
This simplifies to:
\[
\log_{3}\left(\frac{(4 - x)^2}{5}\right) = \log_{3}(45)
\]
Step 3: Eliminate the Logarithm
Since the logarithms are equal, we can set the arguments equal to each other:
\[
\frac{(4 - x)^2}{5} = 45
\]
Step 4: Solve for \( x \)
Multiplying both sides by 5 gives:
\[
(4 - x)^2 = 225
\]
Taking the square root of both sides results in:
\[
4 - x = 15 \quad \text{or} \quad 4 - x = -15
\]
Solving these equations:
\( 4 - x = 15 \) leads to \( x = -11 \)
\( 4 - x = -15 \) leads to \( x = 19 \)
Step 5: Check for Validity
We need to ensure that the solutions do not make the logarithm undefined. For \( x = -11 \):
\[
4 - (-11) = 15 > 0 \quad \text{(valid)}
\]
For \( x = 19 \):
\[
4 - 19 = -15 < 0 \quad \text{(invalid)}
\]
Thus, the only valid solution is \( x = -11 \).