Math Problem Statement

Solve the logarithmic equation 2log6(x - 5) + log6(9) = 2.

Solution

The equation provided is:

2log6(x5)+log6(9)=22 \log_6(x - 5) + \log_6(9) = 2

Step-by-Step Solution:

  1. Simplify using logarithmic properties: Recall the property alogb(c)=logb(ca)a \log_b(c) = \log_b(c^a). Apply this property to the first term: 2log6(x5)=log6((x5)2)2 \log_6(x - 5) = \log_6((x - 5)^2) So, the equation becomes: log6((x5)2)+log6(9)=2\log_6((x - 5)^2) + \log_6(9) = 2

  2. Combine the logarithms: Use the property logb(a)+logb(c)=logb(ac)\log_b(a) + \log_b(c) = \log_b(a \cdot c). Combine the two logarithmic terms: log6((x5)29)=2\log_6((x - 5)^2 \cdot 9) = 2

  3. Rewrite the equation in exponential form: Recall that logb(A)=C\log_b(A) = C implies A=bCA = b^C. Rewrite the equation: (x5)29=62(x - 5)^2 \cdot 9 = 6^2

  4. Simplify: Compute 62=366^2 = 36: (x5)29=36(x - 5)^2 \cdot 9 = 36 Divide both sides by 9: (x5)2=4(x - 5)^2 = 4

  5. Solve for x5x - 5: Take the square root of both sides (consider both positive and negative roots): x5=±2x - 5 = \pm 2

  6. Solve for xx: Add 5 to both sides: x=5+2=7orx=52=3x = 5 + 2 = 7 \quad \text{or} \quad x = 5 - 2 = 3

  7. Check for validity: The logarithmic argument x5x - 5 must be positive. For x=3x = 3: x5=35=2(invalid, as logarithms of negative values are undefined).x - 5 = 3 - 5 = -2 \quad (\text{invalid, as logarithms of negative values are undefined}). Therefore, the only valid solution is: x=7x = 7

Final Answer:

x=7x = 7

Would you like additional clarification on any step? Here are five related questions to expand on:

  1. How do the properties of logarithms simplify equations like this?
  2. What happens if the base of the logarithm changes?
  3. Why is x=3x = 3 invalid in this context?
  4. Can this type of equation be solved graphically?
  5. How would the solution change if the base of the logarithm was unspecified?

Tip: Always check the domain of the logarithmic function to ensure the arguments are valid!

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Math Problem Analysis

Mathematical Concepts

Logarithms
Properties of Logarithms
Equations

Formulas

a * log_b(c) = log_b(c^a)
log_b(A) + log_b(B) = log_b(A * B)
log_b(A) = C implies A = b^C

Theorems

Logarithmic Properties
Exponential Relationship with Logarithms

Suitable Grade Level

Grades 10-12