Chapter 27: Problem 3
The value of \(\log \left(\frac{18}{14}\right)+\log \left(\frac{35}{48}\right)-\log \left(\frac{15}{16}\right)=\) (1) 0 (2) 1 (3) 2 (4) \(\log _{16} 15\)
Short Answer
Expert verified
Question: Simplify the following logarithmic expression: $\log \left(\frac{18}{14}\right)+\log \left(\frac{35}{48}\right)-\log \left(\frac{15}{16}\right)$.
Answer: (1) 0
Step by step solution
01
Write down the given expression
We are given the expression:
$$\log \left(\frac{18}{14}\right)+\log \left(\frac{35}{48}\right)-\log \left(\frac{15}{16}\right)$$
02
Use the logarithm rules to simplify
We use the logarithm product rule, log(a) + log(b) = log(ab), then use the logarithm quotient rule, log(a) - log(b) = log(a/b) to simplify the given expression:
$$\log \left(\frac{18}{14}\right)+\log \left(\frac{35}{48}\right)-\log \left(\frac{15}{16}\right) = \log \left(\frac{18}{14} \times \frac{35}{48} \div \frac{15}{16}\right)$$
03
Simplify the fractions
Multiply and divide the fractions as follows:
$$\log \left(\frac{18}{14} \times \frac{35}{48} \div \frac{15}{16}\right) = \log \left(\frac{18 \times 35 \times 16}{14 \times 48 \times 15}\right)$$
04
Simplify the numbers
We can cancel out some terms in the numerator and denominator:
$$\log \left(\frac{18 \times 35 \times 16}{14 \times 48 \times 15}\right) = \log \left(\frac{2\times 9 \times 5\times 7 \times 16}{2 \times 7 \times 3 \times 16 \times 15}\right) $$
Now, we cancel out the common factors:
$$\log \left(\frac{2\times 9 \times 5\times 7 \times 16}{2 \times 7 \times 3 \times 16 \times 15}\right) = \log \left(\frac{9 \times 5}{3 \times 15}\right)$$
05
Simplify the remaining expression
Now, we simplify the remaining expression:
$$\log \left(\frac{9 \times 5}{3 \times 15}\right) = \log \left(\frac{45}{45}\right) = \log(1)$$
We know from the properties of logarithm that \(\log(1)=0\).
So, the value of the given expression is:
$$\log \left(\frac{18}{14}\right)+\log \left(\frac{35}{48}\right)-\log \left(\frac{15}{16}\right) = 0$$
The correct answer is (1) 0.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Logarithm Properties
Logarithms are a fundamental part of mathematics used to solve equations involving exponentiation. They help in transforming multiplicative relationships into additive ones, making them easier to handle. Understanding logarithm properties is essential:
- Inverse Property: Logarithms are the inverse of exponentiation. For any positive numbers a and x, if a raised to a certain power equals x (i.e., \(a^y = x\)), then \( y \) is the logarithm of x with base a (i.e., \( \log_a(x) = y \)).
- Identity Property: The logarithm of 1, regardless of the base, is 0, because any number raised to the power of 0 is 1: \( \log_a(1) = 0 \).
- Positive Numbers: Logs are defined only for positive numbers, because a negative number cannot be raised to a power to get a real result.
Logarithm Rules
To solve logarithmic equations, certain rules help simplify expressions:
- Product Rule: This rule states that \( \log(a) + \log(b) = \log(ab) \). It is handy when multiplying numbers inside a log.
- Quotient Rule: Similarly, \( \log(a) - \log(b) = \log\left(\frac{a}{b}\right) \). This rule simplifies subtraction of logs into divisions within a single log.
- Power Rule: This rule illustrates that \( \log(a^b) = b\cdot \log(a) \), allowing for the exponent to be brought out front as a multiplier.
Fraction Simplification
Simplifying fractions is a crucial skill for mathematical problem-solving. In complex equations, like those involving logs, fraction simplification can be a major step in reducing complexity:
- Multiplying and Dividing: When dealing with fractions inside a log equation, multiply the numerators together and the denominators together.
- Cancel Common Factors: Break down numbers into their prime factors and cancel any common factors from the numerator and denominator.
- Reduce to Simplest Form: Always reduce to the simplest form to make solving the overall expression easier.
Mathematical Problem Solving
Mathematical problem solving involves breaking down complex expressions into small, manageable steps. Using a structured approach aids in simplifying and eventually solving equations:
- Identify the Problem: Start by understanding what the problem is asking. In this case, simplification of logarithmic expressions.
- Apply Relevant Techniques: Use mathematical techniques, such as logarithm rules and fraction simplification, to dismantle the problem into simpler parts.
- Perform Step-by-Step Simplification: Move through the problem incrementally, simplifying at each stage, aiming to make calculations easier.
- Check the Solution: Once simplified, verify each step to ensure accuracy, especially when dealing with logarithms where properties can sometimes lead to counterintuitive results.