Chapter 1: Problem 5
Designate each of the given numbers as being an integer, rational, irrational, real, or imaginary. (More than one designation may be correct.) $$3, \quad \sqrt{-4}, \quad-\frac{\pi}{6}, \quad \frac{1}{8}$$
Short Answer
Expert verified
3: integer, rational, real. \( \sqrt{-4} \): imaginary. \( -\frac{\pi}{6} \): irrational, real. \( \frac{1}{8} \): rational, real.
Step by step solution
01
Identify 3
The number 3 is a whole number without any fractional part. It is straightforwardly classified as an integer. Since all integers are also real numbers, 3 is a real number. Furthermore, integers are rational since they can be expressed as a fraction where the denominator is 1, so 3 is a rational number. Thus, 3 is an integer, rational, and real number.
02
Identify \( \sqrt{-4} \)
The expression \( \sqrt{-4} \) involves taking the square root of a negative number. In mathematics, the square root of a negative number involves imaginary units. \( \sqrt{-4} \) can be written as \( 2i \), where \( i \) is the imaginary unit. Therefore, \( \sqrt{-4} \) is an imaginary number.
03
Identify \( -\frac{\pi}{6} \)
The number \( -\frac{\pi}{6} \) is a negative version of a fraction that involves \( \pi \), which is an irrational number. Consequently, \( -\frac{\pi}{6} \) itself is irrational, as any non-zero multiple of an irrational number is also irrational. Furthermore, since it lies on the number line, it is a real number. Thus, \( -\frac{\pi}{6} \) is an irrational and real number.
04
Identify \( \frac{1}{8} \)
The number \( \frac{1}{8} \) is in fraction form where both the numerator and the denominator are integers, and the denominator is not zero. Thus, it can be written as a terminating decimal, making it a rational number. In addition, it is a real number, as all rational numbers are real. Therefore, \( \frac{1}{8} \) is a rational and real number.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integers
An integer is a number without any fractional or decimal part. This means integers are whole numbers, and they can be either positive, negative, or zero. Here are some examples of integers:
- -3 (negative integer)
- 0 (neutral, also considered an integer)
- 7 (positive integer)
Rational Numbers
Rational numbers are numbers that can be written as a ratio, or fraction, of two integers. The key condition is that the denominator is not zero. This means that each rational number can be expressed in the form \( \frac{a}{b} \) where \( a \) and \( b \) are integers and \( b eq 0 \). Some examples:
- \( \frac{3}{4} \) is rational because both 3 and 4 are integers.
- 5 can be considered rational as \( \frac{5}{1} \).
- 0.75 is rational because it can be expressed as \( \frac{3}{4} \).
Irrational Numbers
Irrational numbers are numbers that cannot be written as a simple fraction of two integers. Their decimal expansions are non-repeating, non-terminating. These numbers often involve roots or constants such as \( \pi \) or \( e \). Examples include:
- \( \sqrt{2} \) cannot be precisely expressed as a fraction.
- \( \pi \) is the ratio of the circumference of any circle to its diameter, and it cannot be exactly written as a fraction.
Real Numbers
Real numbers encompass all the numbers on the number line, including both rational and irrational numbers. Essentially, any number you can think of that isn't a product of an imaginary unit \( i \) is a real number. This includes:
- Integers like -5, 0, and 16.
- Fractions and decimals like \( \frac{1}{4} \) or 0.25.
- Irrational numbers like \( \sqrt{3} \) or \( \pi \).
Imaginary Numbers
Imaginary numbers arise when we take the square root of negative numbers. The imaginary unit \( i \) is defined as \( \sqrt{-1} \). By extension:
- \( \sqrt{-16} \) equals \( 4i \) since \( \sqrt{-16} = \sqrt{16} \times \sqrt{-1} = 4 \times i \).
- Any multiple of \( i \) is considered imaginary.