Writing Algebraic Expressions

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Writing Algebraic Expressions
Be able to write an algebraic expression for a
word phrase or write a word phrase for an
expression.
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• Warm Up
• Evaluate each algebraic expression for the given
  value of the variables.
• ) 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
8 y
86
23
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Although they are closely related, a Great Dane
weighs about 40 times as much as a Chihuahua.
An expression for the weight of the Great Dane
could be 40c, where c is the weight of the
Chihuahua.
When solving real-world problems, you will need
to translate words, or verbal expressions, into
algebraic expressions.
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Notes

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

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On the back of your notes
Addition Subtraction
Multiplication Division
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Addition Phrases

• More than
• Increase by
• Greater than
• Add
• Total
• Plus
• Sum

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Subtraction Phrases

• Decreased by
• Difference between
• Take Away
• Less
• Subtract
• Less than
• Subtract from

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Multiplication Phrases

• Product
• Times
• Multiply
• Of
• Twice or double
• Triple

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Division Phrases

• Quotient
• Divide
• Divided by
• Split equally

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Notes

• Multiplication expressions should be written in
  side-by-side form, with the number always in
  front of the variable.
• 3a 2t 1.5c 0.4f

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Notes

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

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Examples

• Addition phrases
• 3 more than x
• the sum of 10 and a number c
• a number n increased by 4.5

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Examples

• Subtraction phrases
• a number t decreased by 4
• the difference between 10 and a number y
• 6 less than a number z

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Examples

• Multiplication phrases
• the product of 3 and a number t
• twice the number x
• 4.2 times a number e

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Examples

• Division phrases
• the quotient of 25 and a number b
• the number y divided by 2
• 2.5 divide g

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Examples

• converting 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

12f
75h
10w
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Examples

• converting 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
• childrens tickets at y dollars each

5x
3y
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Examples

• the total cost for 5 adult tickets and 3
  childrens tickets using the dollar amounts from
  the previous two problems

5x 3y Total Cost
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Example
The United States House of Representatives has 35
more members than four times the number of
members in the United States Senate. Define a
variable and write an expression to represent the
number of members in the House of Representatives.