## CONTENT

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We call equation the equality between two algebraic expressions, functions of the same variables, which is verified only for values that are attributed to these variables. The expression on the left of the equality symbol is called the first member, the one on the right is called the second member. The variables of the two expressions are called in unknown.

** **** What is an Equation**

** **An equation says that two things are equal.

It will have an equals sign "=" like this:

7 + 2 = 10 − 1

That equation says: what is on the left (7 + 2) is equal to what is on the right (10 − 1)

So an equation is like a statement "this equals that"

Here is another equation:

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## Parts of an Equation

So people can talk about equations, there are **names** for different parts (better than saying "that thingy there"!)

Here we have an equation that says 4x − 7 equals 5, and all its parts:

A **Variable** is a symbol for a number we don't know yet. It is usually a letter like x or y.

A number on its own is called a **Constant**.

A **Coefficient** is a number used to multiply a variable (**4x** means **4** times **x**, so **4** is a coefficient)

Variables on their own (without a number next to them) actually have a coefficient of 1 (**x** is really **1x**)

Sometimes a coefficient is a letter like **a** or **b** instead of a number:

### Example: ax2 + bx + c

**x**is a variable**a**and**b**are coefficients**c**is a constant

An **Operator** is a symbol (such as +, ×, etc) that shows an operation (ie we want to do something with the values).

A **Term** is either a single number or a variable, or numbers and variables multiplied together.

An **Expression** is a group of terms (the terms are separated by + or − signs)

So, now we can say things like "that expression has only two terms", or "the second term is a constant", or even "are you sure the coefficient is really 4?"

** **

** **

** What is an Equation**

** **An equation says that two things are equal.

It will have an equals sign "=" like this:

7 + 2 = 10 − 1

That equation says: what is on the left (7 + 2) is equal to what is on the right (10 − 1)

So an equation is like a statement "this equals that"

Here is another equation:

** **

## Parts of an Equation

So people can talk about equations, there are **names** for different parts (better than saying "that thingy there"!)

Here we have an equation that says 4x − 7 equals 5, and all its parts:

A **Variable** is a symbol for a number we don't know yet. It is usually a letter like x or y.

A number on its own is called a **Constant**.

A **Coefficient** is a number used to multiply a variable (**4x** means **4** times **x**, so **4** is a coefficient)

Variables on their own (without a number next to them) actually have a coefficient of 1 (**x** is really **1x**)

Sometimes a coefficient is a letter like **a** or **b** instead of a number:

### Example: ax^{2} + bx + c

**x**is a variable**a**and**b**are coefficients**c**is a constant

An **Operator** is a symbol (such as +, ×, etc) that shows an operation (ie we want to do something with the values).

A **Term** is either a single number or a variable, or numbers and variables multiplied together.

An **Expression** is a group of terms (the terms are separated by + or − signs)

So, now we can say things like "that expression has only two terms", or "the second term is a constant", or even "are you sure the coefficient is really 4?"

** **