Problem 28 - Algebra A Combined Function

Question

Find the exact value of each logarithm. $$ \log 0.001 $$

Step-by-Step Solution

Answer

\(\log(0.001) = -3\) because \(0.001 = 10^{-3}\).

Step 1: Express as a power of 10

\( 0.001 = 10^{-3} \).

Step 2: Evaluate

\( \log 0.001 = \log 10^{-3} = -3 \).

Key Concepts

logarithm base 10

A logarithm base 10, also known as a common logarithm, is a mathematical operation that helps us determine the power, or exponent, to which 10 must be raised to yield a given number. Common logarithms are denoted simply as \(\log\), meaning \(\log_{10}\). This means that when you see \(\log(x)\), it is assumed to be with base 10, unless specified otherwise.

For example, when you have \(\log(100)\), you're being asked: "To what power do we need to raise 10 to get 100?" Since \(10^2 = 100\), the answer is 2. Therefore, \(\log(100) = 2\).

Understanding the logarithm function with base 10 is crucial because it frequently appears across various fields of science, engineering, and everyday calculations. Whether it's assessing earthquake magnitudes or measuring sound intensity, the common logarithm is a fundamental part of many equations.

logarithm properties

Understanding the properties of logarithms helps to simplify complex logarithmic expressions and solve equations more easily. Let's dive into some essential properties:

• Product Property: \(\log_b(MN) = \log_b(M) + \log_b(N)\)
• Quotient Property: \(\log_b\left(\frac{M}{N}\right) = \log_b(M) - \log_b(N)\)
• Power Property: \(\log_b(M^p) = p \cdot \log_b(M)\)

These properties convert multiplication, division, or power operations into addition, subtraction, or multiplication, respectively, which often makes the math easier to handle.

Additionally, two special properties are particularly important:

• Log of 1: \(\log_b(1)\) is always 0, because any number raised to the power of 0 is 1.
• Log of the base: \(\log_b(b) = 1\), which makes sense as a number raised to the power of 1 remains unchanged.

Using these properties can simplify and solve logarithmic problems efficiently.

exponents

Exponents are a way to express repeated multiplication of a number by itself. The exponent tells us how many times to multiply the base number. For example, \(2^3\) means \(2 \times 2 \times 2 = 8\).

Understanding exponents is key in working with logarithms because logarithms are essentially exponents in reverse. When we use logarithms, we're trying to find which exponent was used with a particular base to get a specific number.

There are a few key principles of exponents:

• Multiplication: \(a^m \times a^n = a^{m+n}\)
• Division: \(\frac{a^m}{a^n} = a^{m-n}\)
• Power of a power: \((a^m)^n = a^{m \times n}\)
• Zero exponent: Any non-zero number raised to the power of 0 is 1, i.e., \(a^0 = 1\).
• Negative exponent: \(a^{-n} = \frac{1}{a^n}\).

These principles are used in manipulating and simplifying expressions, and understanding them helps in getting a firm grasp on how logarithms work since solving a logarithm often involves reversing the exponentiation process.