Variable Expressions 2009 SOL A.1 Varina High School Tammy Wallace

Vocabulary A variable is a symbol, usually a letter, used to represent a unknown quantity. An algebraic expression may contain numbers, variables, operations, and grouping symbols. An algebraic expression may be evaluated by substituting values for the variables in the expression.

How are algebraic expressions used in Algebra? Algebraic expressions can be translated to verbal expressions or word phrases Verbal expressions or word phrases, which describe characteristics of given conditions, can also be translated into algebraic expressions for the purpose of evaluation.

In expressions, there are many different ways to write multiplication: 𝑎𝑏 𝑎∙𝑏 𝑎 𝑏 or 𝑎 𝑏 (𝑎)(𝑏) 𝑎 x 𝑏 We are not going to use the multiplication symbol (#5) any more. Why do you think we will not use this anymore?

Division, on the other hand, is written as: 𝑥 3 𝑥÷3

Here are some phrases you may have listed. The terms with Here are some phrases you may have listed. The terms with * are ones that are often used. Addition Subtraction Multiplication Division Exponents  sum difference produce quotient power of ___ increase  decrease times divided squared plus minus multiplied ratio cubed add subtract   more than less than total

Writing Algebraic Expressions Steps for Writing Algebraic Expressions: Read for understanding Define the variable Translate the words into numbers/variables/operations Write as an expression

Define a variable and write an algebraic expression for each phrase. two times a number plus 5   Read for understanding Define the variable. Translate to numbers Write as an expression 𝟐𝒙+𝟓 two times a number plus 5 This can be whatever you want it to be Let x = “a number” two times a number plus 5 2∙ 𝑥 +5

7 less than three times a number (NOTE: when the words “more than” or “less than” are used, write the expression opposite than how you read it) Read for understanding Define the variable Translate to numbers Write as an expression 𝟑𝒙−𝟕 7 less than 3 times a number Let x = “a number” 7 less than 3 times a number 𝑠𝑜𝑚𝑒𝑡ℎ𝑖𝑛𝑔 −7 3∙ 𝑥

The absolute value of the sum of a number and 5 Read for understanding Define the variable Translate to numbers Write as an expression 𝒙+𝟓 the absolute value of the sum of a number and 5 Let x = “a number” the absolute value of the sum of a number and 5 ? ?+? 𝑥 and 5

The quotient of a number cubed and 12. Read for understanding Define the variable Translate to numbers Write as an expression 𝒙 𝟑 𝟏𝟐 quotient of a number cubed and 12 Let x = “a number” quotient of a number cubed and 12 ? ? 𝑥 3 𝑎𝑛𝑑 12

The square root of the product of 6 and a number squared. Read for understanding Define the variable Translate to numbers Write as an expression 𝟔 𝒙 𝟐 square root of the product of 6 and a number squared Let x = “a number” square root of the product of 6 and a number squared ? ?∙? 6 and 𝑥 2

Write an verbal expression for each algebraic expression 𝟖+𝒂  Answers may vary

Write an verbal expression for each algebraic expression 𝒎 𝟐   Answers may vary

Write an verbal expression for each algebraic expression 𝟑 𝒏 −𝟓 Answers may vary

Write an verbal expression for each algebraic expression 𝒙 𝟐 +𝟔 Answers may vary