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Do Now 9/21/10

Do Now 9/21/10. Take out HW from last night. Text p.68, #20-50 even Copy HW in your planner. (30 problems) Text p. 77, #12-40 evens Text p. 82, #8-36 evens

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Do Now 9/21/10

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  1. Do Now 9/21/10 • Take out HW from last night. • Text p.68, #20-50 even • Copy HW in your planner. (30 problems) • Text p. 77, #12-40 evens • Text p. 82, #8-36 evens • In your journal, define the word PROPERTY, in reference to a “mathematical property.” Then name and describe as many mathematical properties that you can.

  2. 20) -7 (i,r), -2.7 (r), 0.3 (r), ½ (r) 22) -1 (i,r), -3/5 (r), -0.5 (r), -0.4 (r) 24) 3, 3 26) 0, 0 28) -2.7, 2.7 30) 7.9, 7.9 32) 5/6, 5/6 34) -1 1/3, 1 1/3 36) H: A number is negative. C: The absolute value is negative. FALSE: |-3| = 3 38) H: A number is an integer. C: The number is a rational number. TRUE HomeworkText p. 68 #20-50 even

  3. HomeworkText p. 68 #20-50 even • 40) -(-2) is not negative. -|-2| would be negative. • 42) 0.75 • 44) 0 • 46) 1.5 • 48) 1.5 • 50) B 58) a) -10°F with a wind speed of 10mph b) decreases; decreases

  4. Objective • SWBAT identify the properties of real numbers and add and subtract real numbers by playing ‘Real Number’ cards.

  5. Properties of Real Numbers 1). Commutative Property 2). Associative Property 3). Identity Property 4). Inverse Property 5). Property of Zero 6). Property of -1

  6. Commutative Property The order of numbers when you add or multiply numbers does not change the solution. (-2) + 3 = 3 + (-2)(a)+ (b) = (b) + (a) (-2) ·3=3· (-2) (a) ·(b)=(b) · (a) Think of it as COMMUTING to work!

  7. Associative Property REGROUPING of numbers when adding or multiplying does not change the solution (-2 + 3) + 4 = -2+ (3 +4)(a+ b) + c= a+ (b + c) (-5 ·6)· 10= -5 ·(6· 10) (ab)c= a(bc) Think of it as changing your GROUP of friends!

  8. Identity Property “No change” property 5 + 0 = 5 3 x 1 = 3 Think of it as "I" LOOK IN THE MIRRORand see myself! For addition, the sum of any number plus 0 is that number. a + 0 = 0 + a = a For multiplication, the product of any number times 1 is that number. b · 1 = 1b = b

  9. Inverse Property The sum of a number and its opposite is ZERO. 5 + (-5) = 0 (-a) + a = 0 Property of Zero The product of a number and ZERO is ZERO. 5 · 0 = 0 (-a) · 0 = 0

  10. Property of -1 The product of a number and -1 is its opposite. a · (-1) = -a (-1)· 3 = -3 (-x)(-1) = x -(-4) = 4

  11. Practice Practice with Properties More Practice with Properties of Numbers

  12. Adding Real NumbersUsing a Number Line -5 -4 -3 -2 -1 0 1 2 3 4 5 +5 When you ADD a POSITIVE NUMBER -1 + 5 = -1 + 5 = 4

  13. Adding Real NumbersUsing a Number Line -5 -4 -3 -2 -1 0 1 2 3 4 5 -7 When you ADD a NEGATIVE NUMBER 3 + (-7) = 3 + (-7) = -4

  14. Subtracting Real Numbers • When subtracting two integers, ADD the OPPOSITE of the second number to the first. Instead of subtracting ADD the OPPOSITE!! 8 – 5 = - 5 What is the opposite of 5? ADD the OPPOSITE 8 + (-5) = 3

  15. Don’t Subtract…ADD the OPPOSITE!!! -8 – 6 Instead of subtracting ADD the OPPOSITE!! What is the opposite of 6? - 6 ADD the OPPOSITE -8 + (-6) = -14

  16. -83 + 25 |25| = 25 |-83| = 83 - 83 – 25 = 58 Because 83 has a greater absolute value than 25 the answer is “negative”. 53 – 85 “Add the Opposite” 53 + (-85) |53| = 53 |-85| = 85 - 85 – 53 = 32 Because 85 has a greater absolute value than 53 the answer is “negative”.

  17. “Real Number” Cards • Red cards = Negative • Black cards = Positive • Jack = 11, Queen = 12, King =13, Ace = 1 or 14 • Dealer deals each player 2 cards. • The player with the highest pair, gets all the cards from that round. • The player with the most cards at the end of the deck wins! • Round 1: addition • Round 2: subtraction

  18. Homework NJASK7 Prep • Text p. 77, #26-40 even • Text p. 82, #20-38 even

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