10/21/08 Solve with multiplication or division (2-12 B) #26 Warm-up: Solve the following A. B. C. D. E. F. G. x + 5 = 9 x – 34 = 72 124 = x – 39 Assignment: (2-12) B evens or odds AND (2-12) puzzle all Show all steps on graph paper in required format. Quiz corrections are due tomorrow for retakes. Math binder scores will be collected tomorrow for lessons #11- #21

10/21/08 Solve with multiplication or division (2-12 B) #26 Warm-up A. B. C. D. F. G. x + 5= 9 x – 34 = 72 124 = x – 39 E. -5 -5 +34 +34 +39 +39 X = 4 x = 106 163 = x Assignment: (2-12) B evens or odds AND (2-12) puzzle all Show all steps on graph paper in required format. Quiz corrections are due tomorrow for retakes. Math binder scores will be collected tomorrow for lessons #11- #21

• 2 5 10 = 10 5 2 ÷ = Solving Equations by Multiplying or Dividing Course 2 2-12 Solving Equations by Multiplying or Dividing Like addition and subtraction, multiplication and division are inverse operations. They “undo” each other. 2 • 5 10 = 10 5 2 ÷ =

Additional Example 1: Solving an Equation by Multiplication Course 2 2-12 Solving Equations by Multiplying or Dividing Additional Example 1: Solving an Equation by Multiplication Solve the equation = 13. Check your answer. h 2 h 2 = 13 h 2 (2) = 13(2) Think: h is divided by 2, so multiply both sides by 2 to isolate h. h = 26 Check h 2 = 13 26 2 ? = 13 Substitute 26 for h. 13 = 13 ? 26 is a solution. 

MULTIPLICATION PROPERTY OF EQUALITY Course 2 2-12 Solving Equations by Multiplying or Dividing MULTIPLICATION PROPERTY OF EQUALITY You can multiply both sides of an equation by the same number, and the statement will still be true. 3 · 4 = 12 x = y 2 · 3 · 4 = 2 · 12 zx = zy 6 · 4 = 24 If a variable is divided by a number, you can often use multiplication to isolate the variable. Multiply both sides of the equation by the number.

Insert Lesson Title Here Course 2 2-12 Solving Equations by Multiplying or Dividing Insert Lesson Title Here Try This: Example 1 x 5 Solve the equation = 30. Check your answer. x 5 = 30 x 5 (5) = 30(5) Think: x is divided by 5, so multiply both sides by 5 to isolate x. x = 150 Check x 5 = 30 150 5 ? = 30 Substitute 150 for x. 30 = 30 ?  150 is a solution.

Additional Example 2: Solving an Equation by Division Course 2 2-12 Solving Equations by Multiplying or Dividing Additional Example 2: Solving an Equation by Division Solve the equation 51 = 17x. Check your answer. 51 = 17x Think: x is multiplied by 17, so divide both sides by 17 to isolate x. 51 = 17x 17 17 3 = x Check 51 = 17x 51 = 17(3) ? Substitute 3 for x. 51 = 51 ?  3 is a solution.

DIVISION PROPERTY OF EQUALITY Course 2 2-12 Solving Equations by Multiplying or Dividing DIVISION PROPERTY OF EQUALITY You can divide both sides of an equation by the same nonzero number, and the statement will still be true. 5 · 6 = 30 5 · 6 3 = 30 5 · 6 = 10 5 · 2 = 10 x z x = y y = z ≠ 0 You cannot divide by 0. Remember!

Insert Lesson Title Here Course 2 2-12 Solving Equations by Multiplying or Dividing Insert Lesson Title Here Try This: Example 2 Solve the equation 76 = 19y. Check your answer. 76 = 19y Think: y is multiplied by 19, so divide both sides by 19 to isolate y. 76 = 19y 19 19 4 = y Check 76 = 19y 76 = 19(4) ? Substitute 4 for y. 76 = 76 ?  4 is a solution.

Additional Example 3 Continued Course 2 2-12 Solving Equations by Multiplying or Dividing Additional Example 3 Continued Beats in 10s times 6 = beats per minutes b · 6 = 78 Think: b is multiplied by 6, so divide both sides by 6 to isolate b. 6b = 78 6b = 78 6 6 b = 13 Trevor’s heart beats 13 times 10 seconds.

Insert Lesson Title Here Course 2 2-12 Solving Equations by Multiplying or Dividing Insert Lesson Title Here Lesson Quiz: Part 1 Solve the equation. Check your answer. 1. 12 = 4x 2. 18z = 90 3. 12 = 4. 840 = 12y 5. x = 3 z = 5 x 4 x = 48 y = 70 h 22 = 9 h = 198

Show all steps on graph paper in required format. 10/21/08 Solve with multiplication or division (2-12 B) #26 Show all steps on graph paper in required format. (2-12) B evens or odds AND (2-12) puzzle all Quiz corrections are due tomorrow for retakes. Math binder scores will be collected tomorrow for lessons #11- #21