Question
upstudy study bank question image url

Solve the following loganthmic equation. \( \log (8 x+9)=1+\log (x-4) \) Select the correct choice below and, if necessary, fill in the answer box to complete your choice. (b). The solution set is \( \} \). (Simplify your answer. Type an exact answer. Use a comma to separate answers as needed. B. There is no solution.

Ask by Gough Olson. in the United States
Jan 22,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

The solution set is \( \left\{\,\dfrac{49}{2}\,\right\} \).

Solution

To solve the logarithmic equation: \[ \log (8x + 9) = 1 + \log (x - 4) \] **Step 1: Determine the Domain** For the logarithms to be defined: \[ 8x + 9 > 0 \quad \Rightarrow \quad x > -\frac{9}{8} \] \[ x - 4 > 0 \quad \Rightarrow \quad x > 4 \] Thus, the domain is \( x > 4 \). **Step 2: Solve the Equation** Rewrite the equation using logarithmic properties: \[ \log (8x + 9) - \log (x - 4) = 1 \] Combine the logs: \[ \log \left( \frac{8x + 9}{x - 4} \right) = 1 \] Convert from logarithmic to exponential form (assuming base 10): \[ \frac{8x + 9}{x - 4} = 10^1 = 10 \] Solve for \( x \): \[ 8x + 9 = 10(x - 4) \] \[ 8x + 9 = 10x - 40 \] \[ 9 + 40 = 10x - 8x \] \[ 49 = 2x \] \[ x = \frac{49}{2} \] **Step 3: Verify the Solution** Ensure that \( x = \frac{49}{2} \) is within the domain \( x > 4 \): \[ \frac{49}{2} = 24.5 > 4 \] **Conclusion** The solution is valid. **Answer:** The solution set is \( \left\{\,\dfrac{49}{2}\,\right\} \).

Reviewed and approved by the UpStudy tutoring team

error msg
Explain
Simplify this solution

The Deep Dive

To solve the equation \( \log (8x + 9) = 1 + \log (x - 4) \), first, we can use the properties of logarithms to rewrite it. The right side can be transformed as \( \log (10) + \log (x - 4) = \log (10(x - 4)) \). This gives us: \( \log (8x + 9) = \log (10(x - 4)) \). By equating the arguments (since the logarithm is a one-to-one function), we have: \( 8x + 9 = 10(x - 4) \). Expanding and simplifying gives: \( 8x + 9 = 10x - 40 \) => \( 9 + 40 = 10x - 8x \) => \( 49 = 2x \) => \( x = \frac{49}{2} = 24.5 \). It's important to check if this solution falls within the valid domain of the logarithms. We need \( x - 4 > 0\) which implies \( x > 4\) — and since \( 24.5 > 4\), it's valid. Thus, the solution set is \( \{ 24.5 \} \). So the answer is: (b). The solution set is \( \{ 24.5 \} \).

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy