Introduction to Algebra

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

Numerical Expression – a mathematical statement with numbers and an operation, and without an = sign Ex. 5 + 2 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

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!

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