Pre-Algebra Chapter 1-1 Expressions and Variables

Group Work Review Vocabulary: Sum, Difference, Product, Quotient, Factor Use the review vocabulary to complete the statement. – In the multiplication equation 12 5 = 60, 12 and 5 are called _________ and 60 is called the ______. – When you divide one number by another, the result is called the ____________.

Vocabulary Numerical Expression – consists of numbers and operations. (4 5) Variable – a letter used to represent one or more numbers. Variable Expression – consists of numbers, variables and operations. Evaluate – to evaluate or solve a variable expression, substitute a number for each variable and evaluate the resulting numerical expression.

Examples … During its summer feeding season, a blue whale eats about 4 tons of food every day. To find about how many tons of food a blue whale eats in a given number of days, you can multiply the number of days by 4. Evaluate the expression 4 d when d = 120 to find about how many tons of food a blue whale eats in a feeding season of 120 days.

Examples … Evaluate the expression 3 s when s = 60 to find how many miles Doug drives in 3 hours at a speed of 60 miles per hour.

TWO VARIABLES>>> Evaluate the expression when x = 10 and y = 4 – x + y – xy

Checkpoint 1. y – x 3. y – x Evaluate the expression when x = 6 and y = xy

Vocabulary Verbal model – describes a problem using words as labels and using math symbols to relate the words.

Common Words and Phrases that Indicate Operations AdditionSubtractionMultiplicationDivision Plus The sum of Increased by Total More than Added to Minus The difference of Decreased by Fewer than Less than Subtracted from Times The product of Multiplied by Of Divided by Divided into The quotient of

Writing a variable expression You plan to divide the 120 players in a baseball league into teams with the same number of players. Use a verbal model to write a variable expression for the number of teams if you know the number of players on each of them.