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Variables and Expressions

Variables and Expressions. Vocabulary. A variable is a letter or symbol used to represent a number. A constant is a value that does not change; a number. An expression is a math phrase that contains operations/#’s/variables (no = sign). n + 8. variable. constant. expression.

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Variables and Expressions

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  1. Variables and Expressions

  2. Vocabulary A variable is a letter or symbol used to represent a number A constant is a value that does not change; a number An expression is a math phrase that contains operations/#’s/variables (no = sign) n + 8 variable constant expression

  3. Substitution Substitute – replace a variable with a # or another expression Evaluate: n + 8 for n = 3 Step 1 – Write the expression n + 8 Step 2 – Rewrite and substitute the variable’s given value 3 + 8 11 Step 3 – Solve

  4. Writing Expressions The expression… can also be written as x • 3, x(3), 3x x × 3 35 y 35 ÷ y

  5. Examples Evaluate each expression for the given value of the variable: 5x + 2 for x = 4 64 – 12 for d = 2 d 5x + 2 64 – 12 d 5•4 + 2 20 + 2 64 – 12 2 22 32 - 12 20

  6. Using Tables Find the missing values: p = 3, 6•3 = 18 18 p = 4, 6•4 = 24 24

  7. Problem Solving Each touchdown in football is worth 7 points. How many points does a team get for 5 touchdowns? 35 points 7•5 = 35

  8. A football team gets 7 points for every touchdown, and 3 points for every field goal. Their score is: 7T + 3F Calculate the score for each team below, and figure out who won. Team A Touchdowns: 3 Field Goals: 5 Team B Touchdowns: 7 Field Goals:0 36 35

  9. A football team gets 7 points for every touchdown, and 3 points for every field goal. Their score is: 7T + 3F Calculate the score for each team below, and figure out who won. Team A Touchdowns: 2 Field Goals: 1 Team B Touchdowns: 1 Field Goals:3 17 16

  10. Evaluate each expression to find the missing values in the table. 24 ÷ 2 = 12 24 ÷ 6 = 4 24 ÷ 4 = 6 24 ÷ 8 = 3

  11. Evaluate each expression to find the missing values in the table. 1 + 16 = 17 4 + 16 = 20 6 + 16 = 22 10 + 16 = 26

  12. The school store sells candy. Jolly ranchers are $2 per large bag, smarties are $3 per bag, and warheads are $2 per bag. The cost for students is calculated as: 2J + 3S + 2W Calculate the cost for each student below, and figure out who paid more. Student A Jolly Ranchers: 3 Smarties: 5 Warheads: 2 Student B Jolly Ranchers: 1 Smarties: 7 Warheads: 2 $25 $27

  13. The school store sells candy. Jolly ranchers are $2 per large bag, smarties are $3 per bag, and warheads are $2 per bag. The cost for students is calculated as: 2J + 3S + 2W Calculate the cost for each student below, and figure out who paid more. Student A Jolly Ranchers: 2 Smarties: 1 Warheads: 4 Student B Jolly Ranchers: 1 Smarties: 3 Warheads: 0 $15 $11

  14. Evaluate each expression to find the missing values in the table. 4•1 = 4 4•4 = 16 4•6 = 24 4•10 = 40

  15. Evaluate each expression to find the missing values in the table. 25 – 2 = 23 25 – 6 = 19 25 – 10 = 15 25 – 12 = 13

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