Math Problem Statement

Supposed log7(8)=a and log7(13)=b. Use the change-of-base formula along with properties of logarithms to rewrite the expression in terms of a and b

. Show the steps for solving.

log13(8)

Solution

We are given the expressions log7(8)=a\log_7(8) = a and log7(13)=b\log_7(13) = b. Using this information, we want to express log13(8)\log_{13}(8) in terms of aa and bb.

Steps to solve:

  1. Use the change-of-base formula: The change-of-base formula for logarithms states that: logb(x)=logk(x)logk(b)\log_b(x) = \frac{\log_k(x)}{\log_k(b)} where kk can be any base, but for our purposes, we will use base 7.

    So, we can rewrite log13(8)\log_{13}(8) as: log13(8)=log7(8)log7(13)\log_{13}(8) = \frac{\log_7(8)}{\log_7(13)}

  2. Substitute known values: From the problem, we know: log7(8)=aandlog7(13)=b\log_7(8) = a \quad \text{and} \quad \log_7(13) = b Substituting these into the equation: log13(8)=ab\log_{13}(8) = \frac{a}{b}

Thus, the expression for log13(8)\log_{13}(8) in terms of aa and bb is: log13(8)=ab\log_{13}(8) = \frac{a}{b}

Would you like more details or have any questions?

Related questions:

  1. What is the change-of-base formula and why is it useful?
  2. How would the solution differ if a different base were used for the logarithms?
  3. How can logarithmic properties help in simplifying expressions like log13(8)\log_{13}(8)?
  4. Can you use this method for other log bases, such as natural logs or base 10 logs?
  5. How does the property logb(xy)=ylogb(x)\log_b(x^y) = y \log_b(x) factor into solving logarithmic equations?

Tip:

When dealing with logarithms of different bases, the change-of-base formula is a powerful tool for transforming and simplifying expressions.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Change-of-base formula
Properties of logarithms

Formulas

Change-of-base formula: log_b(x) = log_k(x) / log_k(b)
Logarithmic identities: log_b(x/y) = log_b(x) - log_b(y), log_b(x^y) = y * log_b(x)

Theorems

Change-of-base Theorem
Logarithmic Identity Theorems

Suitable Grade Level

Grades 9-12