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Solving Equations by Multiplying or Dividing. 1-8. Warm Up. Problem of the Day. Lesson Presentation. Course 3. Solving Equations by Multiplying or Dividing. 1-8. 4. __. c. Course 3. Warm Up Write an algebraic expression for each word phrase. 1. A number x decreased by 9
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Solving Equations by Multiplying or Dividing 1-8 Warm Up Problem of the Day Lesson Presentation Course 3
Solving Equations by Multiplying or Dividing 1-8 4 __ c Course 3 Warm Up Write an algebraic expression for each word phrase. 1. A number x decreased by 9 2. 5 times the sum of p and 6 3. 2 plus the product of 8 and n 4. the quotient of 4 and a number c x – 9 5(p + 6) 2 +8n
Solving Equations by Multiplying or Dividing 1-8 Course 3 Learn to solve equations using multiplication and division.
Solving Equations by Multiplying or Dividing 1-8 ? 6(8) = 48 ? 48 = 48 Course 3 Additional Example 1A: Solving Equations Using Division Solve 6x = 48. 6x = 48 6x = 48 Divide both sides by 6. 6 6 1 • x = x 1x = 6 x = 8 Check 6x = 48 Substitute 8 for x.
Solving Equations by Multiplying or Dividing 1-8 ? –9(–5) = 45 ? 45 = 45 Course 3 Additional Example 1B: Solving Equations Using Division Solve –9y = 45. –9y = 45 –9y = 45 Divide both sides by –9. –9 –9 1 • y = y 1y = –5 y = –5 Check –9y = 45 Substitute –5 for y.
Solving Equations by Multiplying or Dividing 1-8 ? 9(4) = 36 ? 36 = 36 Course 3 Check It Out: Example 1A Solve 9x = 36. 9x = 36 9x = 36 Divide both sides by 9. 9 9 1 • x = x 1x = 4 x = 4 Check 9x = 36 Substitute 4 for x.
Solving Equations by Multiplying or Dividing 1-8 ? –3(–12) = 36 ? 36 = 36 Course 3 Check It Out: Example 1B Solve –3y = 36. –3y = 36 –3y = 36 Divide both sides by –3. –3 –3 1 • y = y 1y = –12 y = –12 Check –3y = 36 Substitute –12 for y.
Solving Equations by Multiplying or Dividing 1-8 b b b –4 –4 –4 = 5 = 5 –20 ? = 5 –4 ? 5 = 5 Course 3 Additional Example 2: Solving Equations Using Multiplication Solve = 5. –4 • –4 • Multiply both sides by –4. b = –20 Check Substitute –20 for b.
Solving Equations by Multiplying or Dividing 1-8 c c c –3 –3 –3 = 5 = 5 –15 ? = 5 –3 ? 5 = 5 Course 3 Check It Out: Example 2 Solve = 5. –3 • –3 • Multiply both sides by –3. c = –15 Check Substitute –15 for c.
Solving Equations by Multiplying or Dividing 1-8 1 1 1 4 4 4 x = 670 x = 670 Course 3 Additional Example 3: Money Application To go on a school trip, Helene has raised $670, which is one-fourth of the amount she needs. What is the total amount needed? fraction of amount raised so far amount raised so far total amount needed = • = x 670 Write the equation. Multiply both sides by 4. 4• 4• x = 2680 Helene needs $2680 total.
Solving Equations by Multiplying or Dividing 1-8 fraction of total amount raised so far 1 1 1 8 8 8 x = 750 x = 750 Course 3 Check It Out: Example 3 The school library needs money to complete a new collection. So far, the library has raised $750, which is only one-eighth of what they need. What is the total amount needed? amount raised so far total amount needed = • = x 750 Write the equation. 8• Multiply both sides by 8. 8• x = 6000 The library needs to raise a total of $6000.
Solving Equations by Multiplying or Dividing 1-8 x –4 Course 3 Lesson Quiz Solve. 1.3t = 9 2. –15 = 3b 3. = –7 4.z ÷ 4 = 22 5. A roller coaster descends a hill at a rate of 80 feet per second. The bottom of the hill is 400 feet from the top. How long will it take the coaster rides to reach the bottom? t = 3 b = –5 x = 28 z = 88 5 seconds