Inequality Notation
See It in Action
Two examples of the idea done right—and one common look-alike that is not right.
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EXAMPLE
NON-EXAMPLE
Definition
In Algebra 1, inequality notation is used to describe the domain and range of functions, indicating the set of possible input values (domain) and output values (range). Here's how inequality notation applies to each:
Domain
The domain of a function refers to all possible input values (usually x) for which the function is defined. Inequality notation for the domain specifies the set of x values that are valid. For example:
If a function is defined for all real numbers greater than 3, the domain can be written as x > 3.
If the function is defined for all real numbers between -2 and 5, including -2 and 5, the domain is written as -2 < x < 5.
Range
The range of a function refers to all possible output values (usually y) that the function can produce. Inequality notation for the range specifies the set of y values that the function can take. For example:
If the output values are greater than or equal to 4, the range can be written as y > 4
If the output values are between -1 and 3, not including -1 and including 3, the range is written as -1 < y < 3
In summary:
Domain describes the possible values for x (inputs).
Range describes the possible values for y (outputs).
Using inequality notation helps in precisely defining these sets and understanding the constraints of the function.