# Equations and Expressions

# Objective edit

In this lesson, we will cover *variables*, *expressions*, *equations*, and methods of *manipulating* them.

Methods of manipulation include *simplifying*, *substituting*, and *solving*.

# Key Terminology edit

Term | Definition | Part of Speech |
---|---|---|

Variable |
A symbol used to represent a quantity that can change. Variables are numbers. |
Noun |

Expression |
A representation of a quantity that uses numbers or variables, or the mathematical product of both. | Noun |

Equation |
A statement of equality using the symbol . The quantities on each side of the equal sign are the same a each other. |
Noun |

Solution |
A value or values that make equations true. | Noun |

Manipulate |
Modify an expression or an equation in a way that changes what's written on the page. | Verb |

Solve |
Look for solutions | Verb |

Simplify |
Rewrite an expression as a less complicated expression | Verb |

Substitute |
Replace a value with another thing of equal value | Verb |

# Variables and Expressions edit

# Equations edit

A simple equation:

2a+3b+c = 0

This equation has 3 variables (a,b and c);; 3 terms (2a, 3b and c);; and this equation is an equality, because here is an equal sign (=) between both sides of the equation.

Next: solution to a simple algebra problem. Solve the following equation for (a):

- -- - - - - - - - - Some trig stuff:

sin ɵ = Opposite-Side/Hypotenuse

cos ɵ = Adjacent-Side/Hypotenuse

ø