Variables and Expressions 1.3

Vocabulary Algebra: Branch of mathematics that uses symbols such as variables Variable: A letter or symbol used to represent an unknown value. Example: x, y

Vocabulary Algebraic Expression: An expression containing at least one variable and at least one operation. Example: 4-x, 5m +6, ab Defining a Variable: Choosing a variable to represent an unknown quantity

Translate each phrase into an algebraic expression Identify key word for the operation Define your variable Translate from left to right

Key Words for Operations Add More than; sum of; greater than; added to; increased by, Subtract Less than; fewer than; subtracted from; minus; difference of; decreased by Multiply Times; product of; multiplied by Divide Divided by; quotient of; Order is always left to right EXCEPT words with “than”

Ex 1: Three dollars more than the cost of a sandwich more than : add and switch order C= cost of sandwich 3+c but need to switch order because of the word than!! Answer: C+3

Ex 2: Five points more than the points scored by field goals if each field goal is worth 3 points. More than: add and switch order Each goal is worth 3 points: multiply by 3 f= field goals 5+3f but because it says the word than switch the order. Answer: 3f +5

Substitution Property of Equality If two quantities are equal, then one can be replaced by the other.

Evaluate: if x=3, y=4, z=7 Ex 3: 6y-4x Ex 4: 5z+(x+4y)-15

Evaluate: if x=3, y=4, z=7 Ex 5:

Example 6: Suzanne Middle School sold tickets for a school play. The price of an adult ticket was $3, and the price of a student ticket was $1. Write an expression for the total amount of money collected. Suppose 70 adult tickets and 85 student tickets were sold. How much was collected?

Homework Page 16-17 (12-37, 39, 40)