## What is interval and set notation?

any point in this interval or that interval is a valid solution.

…

If any number is a solution to an equation or inequality, as in x² ≥ 0, then we write ℝ in set notation (“all real numbers”) or (−∞, ∞) in interval notation.

If no number is a solution, as in x² = −5, then we write ∅ in either notation..

## What is the U symbol in interval notation?

We use the union symbol (∪) between these two intervals because we are removing the point x = 0. Notice that on our number line, an open dot indicates exclusion of a point, a closed dot indicates inclusion of a point, and an arrow indicates extension to −∞ or ∞.

## What is an interval on a graph?

In graph theory, an interval graph is an undirected graph formed from a set of intervals on the real line, with a vertex for each interval and an edge between vertices whose intervals intersect. … The interval graphs include all proper interval graphs, graphs defined in the same way from a set of unit intervals.

## What is an example of interval notation?

We can use interval notation to show that a value falls between two endpoints. … For example, -3≤x≤2, [-3,2], and {x∈ℝ|-3≤x≤2} all mean that x is between -3 and 2 and could be either endpoint.

## How do you write an answer in interval notation?

For example, the solution 3 < x < 5 is written (3,5) in interval notation, because x cannot be equal to 3 or 5. Express your answers in interval notation by graphing the solution on a number line to determine the upper and lower bounds of the variable. Determine the values of the variable that make the inequality true.

## How do you write an inequality in interval notation?

The symbol (∞) indicates the interval is unbounded to the right. Express ordering relationships using the symbol < for “less than” and > for “greater than.” The symbol (−∞) indicates the interval is unbounded to the left. Two inequalities in one statement joined by the word “and” or by the word “or.”

## What does interval notation look like?

Writing Interval Notation Intervals are written with rectangular brackets or parentheses, and two numbers delimited with a comma. The two numbers are called the endpoints of the interval. … When one of the endpoints is included in the interval but the other is not, then the interval is a half-open interval.