Math Problem Statement

Given log_10(7) = 0.8451 and log_10(2) = 0.3010, find log_10(49/4) without using a calculator.

Solution

We are tasked with finding log10(494)\log_{10} \left( \frac{49}{4} \right) without using a calculator, given that:

log107=0.8451andlog102=0.3010\log_{10} 7 = 0.8451 \quad \text{and} \quad \log_{10} 2 = 0.3010

Steps to solve:

  1. Use the quotient rule of logarithms: log10(494)=log1049log104\log_{10} \left( \frac{49}{4} \right) = \log_{10} 49 - \log_{10} 4

  2. Break down 4949 and 44 using properties of logarithms: log1049=log10(72)=2log107\log_{10} 49 = \log_{10} \left( 7^2 \right) = 2 \log_{10} 7 log104=log10(22)=2log102\log_{10} 4 = \log_{10} \left( 2^2 \right) = 2 \log_{10} 2

  3. Substitute the given values: log1049=2×0.8451=1.6902\log_{10} 49 = 2 \times 0.8451 = 1.6902 log104=2×0.3010=0.6020\log_{10} 4 = 2 \times 0.3010 = 0.6020

  4. Now calculate log10(494)\log_{10} \left( \frac{49}{4} \right): log10(494)=1.69020.6020=1.0882\log_{10} \left( \frac{49}{4} \right) = 1.6902 - 0.6020 = 1.0882

Thus, the value of log10(494)\log_{10} \left( \frac{49}{4} \right) is 1.0882.

Would you like more details or have any questions? Here are some related questions to deepen your understanding:

  1. How can you use logarithmic properties to simplify other expressions involving fractions?
  2. What is the general quotient rule for logarithms, and why does it work?
  3. How would you handle a similar problem if the numbers inside the logarithm were more complex (e.g., higher powers)?
  4. Can you explain how the change of base formula could be used here if you were not given log107\log_{10} 7?
  5. How could you estimate the value of logarithms for numbers between those you are given?

Tip: Always try to break down large numbers into smaller factors or powers to make logarithmic calculations easier.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Logarithmic Properties
Quotient Rule

Formulas

log_b(x/y) = log_b(x) - log_b(y)
log_b(x^n) = n * log_b(x)

Theorems

Logarithm Quotient Rule
Power Rule for Logarithms

Suitable Grade Level

Grades 10-12