Chapter 4: Problem 97
Consider a function defined as follows. Given \(x,\) the value \(f(x)\) is the exponent above the base of 2 that produces \(x .\) For example, \(f(16)=4\) because \(2^{4}=16\) Evaluate a. \(f(8)\) b. \(f(32)\) c. \(f(2)\) d. \(f\left(\frac{1}{8}\right)\)
Short Answer
Expert verified
a. \(f(8) = 3\)b. \(f(32) = 5\)c. \(f(2) = 1\)d. \(f\left(\frac{1}{8}\right) = -3\)
Step by step solution
01
Understand the Problem
The function defined is the logarithm base 2. Given a number x, we need to find the exponent y such that \(2^y = x\). Therefore, \(f(x) = \log_2 (x)\).
02
Evaluate for f(8)
To find the value of \(f(8)\), determine the exponent y such that \(2^y = 8\).We know that \(8 = 2^3\), hence \(f(8) = 3\).
03
Evaluate for f(32)
To find the value of \(f(32)\), determine the exponent y such that \(2^y = 32\).We know that \(32 = 2^5\), hence \(f(32) = 5\).
04
Evaluate for f(2)
To find the value of \(f(2)\), determine the exponent y such that \(2^y = 2\).We know that \(2 = 2^1\), hence \(f(2) = 1\).
05
Evaluate for f(\(\frac{1}{8}\))
To find the value of \(f\left(\frac{1}{8}\right)\), determine the exponent y such that \(2^y = \frac{1}{8}\).We know that \(\frac{1}{8} = 2^{-3}\), hence \(f\left(\frac{1}{8}\right) = -3\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponentiation
Exponentiation is a mathematical operation that involves taking a base number and raising it to a power. The expression for exponentiation is written as \(b^y\), where \(b\) is the base and \(y\) is the exponent. For example, \(2^3 = 8\) means that the base 2 is multiplied by itself three times to get 8.
Here are some key points about exponentiation:
Here are some key points about exponentiation:
- The base can be any real number.
- The exponent can be positive, negative, or zero.
- When the exponent is positive, the base is multiplied by itself. For instance, \(2^4 = 2 \times 2 \times 2 \times 2 = 16\).
- When the exponent is zero, any nonzero base raised to the power of zero equals 1. For example, \(5^0 = 1\).
- When the exponent is negative, the result is the reciprocal of the base raised to the positive exponent. For example, \(2^{-3} = \frac{1}{2^3} = \frac{1}{8}\).
Base 2 Logarithm
The base 2 logarithm, or binary logarithm, is the inverse operation of exponentiation with base 2. The mathematical notation is \(\log_2(x)\), which reads as 'log base 2 of x'. It means finding the exponent \(y\) such that \(2^y = x\).
For instance:
For instance:
- For \(\log_2(8)\), since \(8 = 2^3\), it follows that \(\log_2(8) = 3\).
- For \(\log_2(32)\), since \(32 = 2^5\), it follows that \(\log_2(32) = 5\).
- \(\log_2(1) = 0\) because \(2^0 = 1\).
- \(\log_2(2) = 1\) because \(2^1 = 2\).
- \(\log_2(\frac{1}{8}) = -3\) because \(\frac{1}{8} = 2^{-3}\).
Function Evaluation
Function evaluation involves finding the output of a function given a specific input value. For the function \(f(x) = \log_2(x)\), we evaluate it by determining the exponent that the base 2 must have to equal the input \(x\).
Let’s go through some examples from the problem:
Let’s go through some examples from the problem:
- For \(f(8)\), since \(8 = 2^3\), \(f(8) = 3\).
- For \(f(32)\), since \(32 = 2^5\), \(f(32) = 5\).
- For \(f(2)\), since \(2 = 2^1\), \(f(2) = 1\).
- For \(f\left(\frac{1}{8}\right)\), since \(\frac{1}{8} = 2^{-3}\), \(f\left(\frac{1}{8}\right) = -3\).
Inverse Operations
Inverse operations are pairs of mathematical operations that reverse the effect of each other. In the case of logarithms and exponentiation, these are inverse operations.
When you exponentiate a number, and then take the logarithm of the result, you essentially return to the original number. Mathematically, this is expressed as:
When you exponentiate a number, and then take the logarithm of the result, you essentially return to the original number. Mathematically, this is expressed as:
- \(\log_b(b^y) = y\)
- \(b^{\log_b(x)} = x\)
- \(\log_2(2^3) = 3\)
- \(2^{\log_2(8)} = 8\)