Math Problem Statement
solve for this with step by step solution with laws a. log 15x = log 30 b. log (3x-2)=2 c. log 9 + log (x-8)=4 d. log (x+1) = log 2x e. ln (x+2) -ln (x-7) = ln 6
Solution
Let's solve each equation step by step, using logarithmic laws. I'll explain the key steps along the way.
Problem (a):
Solution:
- Since , we can equate the arguments because the logs are equal:
- Divide both sides by 15:
- Solution: .
Problem (b):
Solution:
- Rewrite the equation in exponential form (using the fact that if , then ):
- Simplify to get:
- Add 2 to both sides:
- Divide by 3:
- Solution: .
Problem (c):
Solution:
- Use the product rule of logarithms: .
- Rewrite in exponential form:
- Calculate :
- Divide by 9:
- Add 8 to both sides:
- Solution: .
Problem (d):
Solution:
- Since , equate the arguments:
- Rearrange the equation:
- Solution: .
Problem (e):
Solution:
- Use the quotient rule of logarithms: .
- Since , equate the arguments:
- Cross-multiply:
- Expand the right side:
- Rearrange to solve for :
- Divide by 5:
- Solution: .
Let me know if you need further details on any step!
Related Questions:
- What are the common logarithmic properties used in problem-solving?
- How can you verify solutions in logarithmic equations?
- What happens if there is no solution for a logarithmic equation?
- What is the difference between logarithmic and exponential equations?
- Can logarithmic equations have complex solutions?
Tip:
Always check the domain of the variables in logarithmic equations to avoid undefined expressions (e.g., arguments of logs must be positive).
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Math Problem Analysis
Mathematical Concepts
Logarithms
Algebra
Logarithmic Equations
Formulas
log_a(b) = c -> b = a^c
log_a(b) + log_a(c) = log_a(bc)
log_a(b) - log_a(c) = log_a(b/c)
Theorems
Equality of Logarithmic Arguments
Suitable Grade Level
Grades 10-12