A mathematical expression that has an equal sign and linear expressions, variable and a number that you don't know, often represented by "x" or "y" forms a linear equation.

Variable(s) in linear expressions

- Cannot have exponents (or powers)

**For example:** xsquared or x2

- Cannot multiply or divide each other

**For example:** "x" times "y" or xy; "x" divided by "y" or x/y

- Cannot be found under a root sign or square root sign (sqrt)

**For example:** √x or the "square root x"; sqrt (x)

A mathematical statement that performs functions of addition, subtraction, multiplication, and division.

**Examples of linear expression**

- x + 4
- 2x + 4
- 2x + 4y

y² |
(no exponents on variables) |

6xy + 4 |
(can't multiply two variables) |

4x / 8y |
(can't divide two variables) |

√y |
(no square root sign on variables) |

**Find x if: ***4x + 8 = 20*

1. |
Isolate "x" to one side of the equation |
4x + 8 - 8 = 20 - 8 4x = 12 |

2. |
Divide both sides by 2: |
4x / 2 = 12 / 2 2x = 6 X=3 |

3. |
Check your work with the original equation: |
4x + 8 = 20 |

**Find x if: ***8x - 4y = 8*

(using more than one variable)

1. |
First step is to isolate "x" |
4x - 4y + 4y = 8 + 4y |

2. |
Second step is to divide both sides by 4: |
4x / 4 = (8 + 4y) / 4 |

3. |
Check your work with the original equation: |
4 * (2 + y) - 4y = 8 |