Warm UpEvaluate each algebraic expression for the

given value of the variables.

1.) 7x + 4 for x = 6

2.) 8y – 22 for y = 9

3.) 12x + for x = 7 and y = 4

4.) y + 3z for y = 5 and z = 6

46

50

868y

23

Do Now

Simplify the following expression:

3x (x + y – 3)

Writing Algebraic Expressions

Objective:

Be able to write an algebraic expression for a word phrase or write a

word phrase for an expression.

Although they are closely related, a Great Dane weighs about 40 times as much as a Chihuahua.

When solving real-world problems, you will need to translate words, or verbal expressions, into algebraic expressions.

An expression for the weight of the Great Dane could be 40c, where c is the weight of the Chihuahua.

Notes

In order to translate a word phrase into an algebraic expression, we must first know some key word phrases for the basic operations.

With a Partner, come up with 3

words or phrases that represent:Addition Subtraction

Multiplication Division

Addition Phrases:More than

Increase by

Greater than

Add

Plus

Sum

Subtraction Phrases:Decreased by

Difference between

Take Away

Minus

Subtract

Less than

Multiplication Phrases:Product

Times

Multiply

Groups of

Twice or double

Triple

Division Phrases:Quotient

Divided by

Split equally

QuantityQuantity: is defined as an amount, measure or number.

Write this as an expression: x times the quantity of 5 subtracted from 9

Answer: x(9-5)

NotesMultiplication expressions should be written in side-by-side form, with the number always in front of the variable.

3a 2t 1.5c 0.4f

NotesDivision expressions should be written using the fraction bar instead of the traditional division sign.

2

c5

t 3

x

ExamplesAddition phrases:

3 more than x

the sum of 10 and a number c

a number n increased by 4.5

ExamplesSubtraction phrases:

a number t decreased by 4

the difference between 10 and a number y

6 less than a number z

ExamplesMultiplication phrases:

the product of 3 and a number t

twice the number x

4.2 times a number e

ExamplesDivision phrases:

the quotient of 25 and a number b

the number y divided by 2

2.5 divide g

Examplesconverting f feet into inches

a car travels at 75 mph for h hours

the area of a rectangle with a length

of 10 and a width of w

Examplesconverting i inches into feet

the cost for tickets if you purchase 5 adult tickets at x dollars each

the cost for tickets if you purchase 3 children’s tickets at y dollars each