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WRITING AND EVALUATING ALGEBRAIC EXPRESSIONS

WRITING AND EVALUATING ALGEBRAIC EXPRESSIONS. Algebra Review Unit. Algebra magic. 1. Think of a number – shh! Don’t tell me! 2. Double it in your head. 3. Add 6. 4. Divide by 2. 5. Subtract the original number from your new number – shh! Let me guess the number you ended up with….

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WRITING AND EVALUATING ALGEBRAIC EXPRESSIONS

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  1. WRITING AND EVALUATING ALGEBRAIC EXPRESSIONS Algebra Review Unit

  2. Algebra magic 1. Think of a number – shh! Don’t tell me! 2. Double it in your head. 3. Add 6. 4. Divide by 2. 5. Subtract the original number from your new number – shh! Let me guess the number you ended up with…..

  3. Did you get… 3 I bet you’re wondering how I knew that! Let’s use some algebra to find out!

  4. Let’s translate our words into algebra WORDS ALGEBRA 1. Think of a number. 2. Double it in your head. 3. Add 6. 4. Divide by 2. 5. Subtract the original number from your new number. Let’s call our number n n + n = 2n 2n + 6 2n + 6 simplifies to: n + 3 2 n + 3 – n simplifies to: 3

  5. Let’s review some important vocabulary words • A variableis a symbol that represents one or more numbers. • Examples of variables are: n number of students t time in minutes x may represent any number for any reason • A termis a number, variable or the product of a number and variable(s). • Examples of terms are: 3x z 2ab 5y3

  6. A coefficientis the numeric factor of your term. • An algebraic expressionis a mathematical phrase with at least one variable. • Examples of algebraic expressions are: 3m 4t + 12 2x - 3 n + 8

  7. algebraic expressions can represent word phrases

  8. Key words and phrases used to describe mathematical operations

  9. Write an algebraic expression for each word phrase • swimming m meters per minute for 3 minutes • 12 heartbeats more than xheartbeats • a price p decreased by 16 • the quotient of q and 6 3m x + 12 p - 16 q 6

  10. The cost of a package of markers is d dollars. Write an algebraic expression for the total cost in dollars of 7 packages of markers. WORDS: NUMBER OF PACKAGESTIMESCOST PER PACKAGE Let d = cost per package An algebraic expression for the total cost in dollars is 7d

  11. Nine students will purchase b books each. Write an algebraic expression for the total number of books the students will buy. WORDS: NUMBER OF STUDENTSTIMES# OF BOOKS PURCHASED EACH Let b = # of books purchased each An algebraic expression for the total number of books is 9b

  12. What is the cost of one pen if a package of 12 pens costs d dollars? WORDS: COST PER PACKAGEDIVIDED BY# OF PENS IN PACKAGE Let d = cost per package An algebraic expression for the total cost in dollars is d 12

  13. we can also write word phrases from algebraic expressions • Write three different word phrases for x + 2 • a number plus 2 • a number increased by 2 • two more than a number • Write three different word phrases for c - 50 • a number minus 50 • a number decreased by 50 • 50 less than a number

  14. steps for evaluating algebraic expressions • Replace the variables with the values that have been given. • Follow the rules for the order of operations. Example: Evaluate 50 – 3x when x = 7 a. write the expression 50 – 3x b. replace the variable with its given value 50 – 3(7) c. multiply 50 – 21 d. subtract29

  15. Evaluate these algebraic expressions • 8x + 2 let x = 3 • 9nlet n = 4 6 • 10ab – 15 let a = 2 let b = 5 8(3) + 2 24 + 2 26 9(4) 6 36 = 6 6 10(2)(5) – 15 20(5) – 15 100 – 15 85

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