Algebraic Conversions and Substitution

Converting Words into Algebra

• In algebra, letters represent numbers; these letters are called variables.

• The term "any number" can be represented by a variable.

• An algebraic expression example: "n+5"

• A variable's value can change or vary.

Substitution

• Substitution in algebra means replacing a variable (letter) with a number to solve the expression.

• Replace pronumerals with their given values.

Example:

If a = 1, evaluate the expression 9 + 2b when b = 3.

9 + 2b = 1 + 2 \times 3

= 1 + 6

= 7

Examples: Write an algebraic expression for the result of each statement

a) Think of a number (n), multiply it by 3, and then subtract 5.

n \times 3 - 5 = 3n - 5

b) Think of a number (n), subtract 5, and then multiply by 3.

(n - 5) \times 3 = 3(n - 5)