This week, we learned Relations and Functions Lesson #2~#9, I think this is a fun but very hard unit. Because there are many new proper nouns and the need to remember 😂.

Relation:A relation is a set of inputs and outputs, often written as ordered pairs (input, output)

Functions:A function is a relation in which each input has only one output.

When representing a relation, we often regard the values of the independent variable as the **input** and the values of the dependent variable as the **output**.

The input values make up the **domain** of the relation ,and the output values make up the **range** of the relation.

The **domain** of a relation is the set of all possible values which can be used for the input of the** independent variable**(x)

The **range** of a relation is the set of all possible values of the output of the **dependent variable**.(y)

The following is a question I made when I first started to do a question(How to answer it is also written on the paper)