1. Introduction to Algebra

2. Vocabulary addition is the inverse of subtraction
Variable – a lower case letter (from a-z) that is used to represent an unknown amount Ex. s, t, g
Constant – a number Ex. 3, 71, 296
Coefficient – a number before a variable in a multiplication expression Ex. 9j
Operation – addition, subtraction, multiplication or division
Inverse – the opposite operation
addition is the inverse of subtraction
subtraction is the inverse of addition
multiplication is the inverse of division
division is the inverse of multiplication

3. Numerical Expression – a mathematical statement with numbers and an operation, and without an = sign Ex
Algebraic Expression – a mathematical statement with numbers and variables, without an = sign Ex. r - 32
Equation – a mathematical statement with an = sign and an answer Ex. 6t = 12
Substitution – replacing the variable with a value Ex. x ÷ 3 = ? for x = 18
18 ÷ 3 = 6

4. Evaluating Expression
Evaluate expressions by substituting the variable for a given amount
Ex. y + 7, for y = 2
Substitute the y for 2
y + 7
2 + 7
= 9
Remember: evaluate means to solve the problem…..
work it out!

5. BTW (By The Way)
In algebra, multiplication is usually written with a coefficient (a number in front of a variable) and a variable: 7c It can also be written: 7(c) (7)(c) 7•c Division is written as a fraction: 36 v
coefficient
variable