VARIABLES, EXPRESSIONS AND FORMULAS

VOCABULARY

Variable – a letter used to represent one or more numbers

Values – numbers

Variable expression – a collection of numbers, variables, and operations

Evaluate the expression – replace each variable in an expression by a number

DESCRIBING THE VARIABLE EXPRESSION

EXAMPLES OF VARIABLE EXPRESSIONS

(What does each expression ask you to do?)

EVALUATE

EVALUATE REAL-LIFE EXPRESSIONS Find the average speed (in miles per hour) of a car

that traveled 180 miles from Hartford, Connecticut to Matawan, New Jersey in 3 hours.

Rate of speed (r) = Distance (d)/Time (t)

Rate = 180 miles/3 hours = 60 miles per hour (mph)

You hike on a trail at 2 miles per hour. How long will it take you to hike if the round-trip distance is 7.4 miles?

Time (t) = Distance (d)/Rate (r)Time = 7.4 miles/2 miles per hour = 3.7 hours

EVALUATE A GEOMETRIC EXPRESSION

2or

2

1 bhAbhA

ExampleFind the area of a triangle with a base of 10 inches and a height of 6 inches.

EVALUATE A GEOMETRIC EXPRESSION

P = a + b + c

ExampleFind the perimeter of a triangle with side lengths 3 inches, 9 inches, and 11 inches.