Problem 47 - College Algebra with Corequisite Support

Question

For the following exercises, write the interval in set-builder notation. \((-\infty, 6)\)

Step-by-Step Solution

Answer

The interval \\( (-\infty, 6) \\) in set-builder notation is \\({x \mid x < 6}\\).

Step 1: Understand Interval Notation

The given interval \((-\infty, 6)\) means all numbers less than 6, starting from negative infinity and approaching 6 but not including 6 itself.

Step 2: Express Interval in Set-Builder Notation

In set-builder notation, we describe a set by a condition that its members satisfy. For \((-\infty, 6)\), the condition is that all numbers, say \(x\), are less than 6. Thus, the set-builder notation is \({x \mid x < 6}\), which translates to 'the set of all numbers x such that x is less than 6.'

Key Concepts

Set-Builder Notation

Set-builder notation is a compact and precise way to describe a set of numbers based on a common property or condition they fulfill. It uses a specific syntax that often includes a variable, a condition, and sometimes a description of the context of that variable.
In the notation \({x \mid x < 6}\), the curly brackets represent the idea of a set. The vertical bar \(|\) can be read as 'such that' or 'where'.
Inside the brackets, the expression tells us: "We have a variable, \(x\), and those \(x\) must satisfy the condition \(x < 6\)."
This clearly specifies everything in the set without having to list out all possible elements, which is especially useful for infinitely large sets. It's a powerful notation that is frequently used in mathematics to clearly specify all numbers in a given range or meeting a certain condition.

Inequalities

Inequalities are mathematical statements that express the relative size or order of two values. Instead of equality, where two values are the same, inequalities allow us to express a range of possibilities.
The inequality \(x < 6\) is a way to convey that \(x\) can be any number less than 6. This includes numbers like 5, 4.9, and 0, but notably, it does not include 6 itself.
Here are a few elements about inequalities that are good to know:

• 'Less than' is represented by the symbol \(<\).
• 'Less than or equal to' uses the symbol \(\leq\).
• 'Greater than' is shown with \(>\).
• 'Greater than or equal to' is indicated by \(\geq\).

Understanding these symbols allows us to navigate different mathematical expressions and conditions, which is crucial when dealing with statements involving range, limits, or specific restrictions in equations.

Mathematical Sets

Mathematical sets are foundational components in mathematics and encompass collections of objects, known as elements, that share a common characteristic. A set might contain numbers, variables, or even other sets.
Sets are generally denoted with curly braces, such as \{1, 2, 3\}, indicating a simple collection of numbers. However, for more complex sets, especially those involving infinite elements, we use set-builder notation.
In mathematics, sets are crucial because they allow mathematicians to group and discuss several objects as a single entity. They reflect a structured way to handle and comprehend data, be it simple collections or more intricate relationships.
Here are some key points about sets:

• An empty set, denoted by \(\emptyset\), contains no elements.
• Sets can be finite, like \{2, 4, 6\}, or infinite, like the set of all positive integers.
• The concept of subsets allows us to talk about parts of a set; for example, \{3\} is a subset of \{1, 2, 3\}.

The structured nature of sets, combined with notations like interval and set-builder, gives mathematicians a robust framework to define and work with numerical concepts.