Math Problem Statement

solve log5 (3x-7)= 2 + log5 2xsolve log5 (3x-7)= 2 + log5 2x

Solution

We are tasked with solving the equation:

log5(3x7)=2+log5(2x)\log_5 (3x - 7) = 2 + \log_5 (2x)

Step 1: Apply logarithmic properties

We can start by applying the logarithmic property:

logbAlogbB=logb(AB)\log_b A - \log_b B = \log_b \left( \frac{A}{B} \right)

First, subtract log5(2x)\log_5 (2x) from both sides:

log5(3x7)log5(2x)=2\log_5 (3x - 7) - \log_5 (2x) = 2

Now, using the logarithmic property, the left side becomes:

log5(3x72x)=2\log_5 \left( \frac{3x - 7}{2x} \right) = 2

Step 2: Rewrite in exponential form

The next step is to rewrite the logarithmic equation in its exponential form. Remember that:

logb(A)=CmeansA=bC\log_b (A) = C \quad \text{means} \quad A = b^C

Thus, we can rewrite:

3x72x=52\frac{3x - 7}{2x} = 5^2

Since 52=255^2 = 25, we get:

3x72x=25\frac{3x - 7}{2x} = 25

Step 3: Solve for xx

Now, solve this equation for xx. First, multiply both sides by 2x2x to eliminate the denominator:

3x7=252x3x - 7 = 25 \cdot 2x

3x7=50x3x - 7 = 50x

Now, move all terms involving xx to one side:

3x50x=73x - 50x = 7

47x=7-47x = 7

Finally, divide by 47-47:

x=747x = \frac{7}{-47}

Thus, the solution is:

x=747x = -\frac{7}{47}

Conclusion:

The value of xx is x=747x = -\frac{7}{47}.

Would you like more details or have any questions?

Here are 5 related questions to expand on this:

  1. How would the solution change if the base of the logarithms was different?
  2. Can you solve a similar equation using natural logarithms (ln\ln)?
  3. What are the general properties of logarithmic functions?
  4. How does the change of base formula work with logarithms?
  5. How can you verify if the solution is valid for the original equation?

Tip: Always check if the solution is within the domain of the logarithmic functions to ensure it is valid!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Logarithms
Algebraic Manipulation
Exponential Functions

Formulas

log_b A - log_b B = log_b (A / B)
log_b (A) = C means A = b^C

Theorems

Properties of Logarithms
Exponential Rewriting Theorem

Suitable Grade Level

Grades 10-12