2-7 Multiplication Equations
 2-7 Multiplication Equations




               Warm Up
               Problem of the Day
               Lesson Presentation




Course 1
Course 1
Course 1
2-7 Multiplication Equations

    Warm Up
    Divide.

       72
    1. 12     6    2. 65 13
                      5


                      40
    3. 60
       6
              10   4. 10   4


      130
    5. 5      26   6. 91 13
                      7

Course 1
2-7 Multiplication Equations


    Problem of the Day
    Katie’s little brother is building a tower with
    blocks. He adds 6 blocks and then removes
    4 blocks. If he adds 8 more blocks, the
    tower will have twice as many blocks as
    when he started. How many blocks did he
    start with?
    10 blocks



Course 1
2-7 Multiplication Equations




   Learn to solve whole-number multiplication
   equations.




Course 1
2-7 Multiplication Equations

      Division is the inverse of multiplication. To
      solve an equation that contains multiplication,
      use division to “undo” the multiplication.


           4m = 32
                           Caution !
           4m = 32
                           4m means “4 × m.”
            4   4
            m=8




Course 1
2-7 Multiplication Equations

      Additional Example 1A: Solving Multiplication
                      Equations
   Solve the equation. Check your answer.
           5p = 75    p is multiplied by 5.
           5p = 75    Divide both sides by 5 to undo
            5    5    the multiplication.
            p = 15

 Check 5p = 75
          ?
     5(15)= 75        Substitute 15 for p in the equation.
          ?
       75 = 75       15 is the solution.


Course 1
2-7 Multiplication Equations

    Additional Example 1B: Solving Multiplication
                     Equations
  Solve the equation. Check your answer.
           16 =    8r    r is multiplied by 8.
           16 =    8r   Divide both sides by 8 to undo
            8       8   the multiplication.
            2=    r
  Check 16 = 8r
              ?
           16 = 8(2)    Substitute 2 for r in the equation.
              ?
           16 = 16     2 is the solution.



Course 1
2-7 Multiplication Equations

                   Check It Out: Example 1A
    Solve the equation. Check your answer.
           8a = 72       a is multiplied by 8.
           8a = 72       Divide both sides by 8 to undo
            8   8        the multiplication.
            x=9
  Check 8a = 72
               ?
           8(9)= 72      Substitute 9 for a in the equation.
               ?
            72 = 72     9 is the solution.



Course 1
2-7 Multiplication Equations

                  Check It Out: Example 1B
    Solve the equation. Check your answer.
        18 = 3w      w is multiplied by 3.
           18 = 3w      Divide both sides by 3 to undo
            3   3       the multiplication.
            6=w
  Check 18 = 3w
              ?
           18 = 3(6)    Substitute 6 for w in the equation.
              ?
           18 = 18     6 is the solution.



Course 1
2-7 Multiplication Equations

  Additional Example 2: Problem Solving Application


           The area of a rectangle is 56 square
           inches. Its length is 8 inches. What
           is its width?




Course 1
2-7 Multiplication Equations
             Additional Example 2 Continued
     1     Understand the Problem
           The answer will be the width of the rectangle
           in inches.
           List the important information:
           • The area of the rectangle is 56 square inches.
           • The length of the rectangle is 8 inches.
           Draw a diagram to represent this information.


                           56        w

                            8
Course 1
2-7 Multiplication Equations
              Additional Example 2 Continued

      2    Make a Plan
           You can write and solve an equation using
           the formula for area. To find the area of a
           rectangle, multiply its length by its width.


             A = lw                             w
            56 = 8w

                                    l



Course 1
2-7 Multiplication Equations
              Additional Example 2 Continued

     3     Solve

           56 = 8w        w is multiplied by 8.
           56 = 8w        Divide both sides by 8 to undo
            8    8        the multiplication.
            7=w

           So the width of the rectangle is 7 inches.




Course 1
2-7 Multiplication Equations
               Additional Example 2 Continued

     4     Look Back
           Arrange 56 identical
           squares in a rectangle.
           The length is 8, so line up
           the squares in rows of 8.
           You can make 7 rows of 8,
           so the width of the
           rectangle is 7.




Course 1
2-7 Multiplication Equations
             Check It Out: Example 2



           The area of a rectangle is 48 square
           inches. Its width is 8 inches. What is
           its length?




Course 1
2-7 Multiplication Equations
                   Check It Out: Example 2
     1     Understand the Problem
           The answer will be the length of the rectangle in
           inches.
           List the important information:
           • The area of the rectangle is 48 square inches.
           • The width of the rectangle is 8 inches.
           Draw a diagram to represent this information.


                            48          8


                             l
Course 1
2-7 Multiplication Equations
            Check It Out: Example 2 Continued

      2    Make a Plan
           You can write and solve an equation using the
           formula for area. To find the area of a
           rectangle, multiply its length by its width.


             A = lw                           w
            48 = l8

                                   l



Course 1
2-7 Multiplication Equations
            Check It Out: Example 2 Continued

     3     Solve

     48 = 8l           l is multiplied by 8.
     48 = 8l           Divide both sides by 8 to undo
      8    8           the multiplication.
       6=l

    So the length of the rectangle is 6 inches.




Course 1
2-7 Multiplication Equations
             Check It Out: Example 2 Continued

     4     Look Back
           Arrange 48 identical
           squares in a rectangle.
           The width is 8, so line up
           the squares in columns of
           8. You can make 6
           columns of 8, so the
           length of the rectangle is
           6.




Course 1
2-7 Multiplication Equations

                      Lesson Quiz

  1. 10y = 300    y = 30
  2. 2y = 82     y = 41
  3. 63 = 9y      y=7
  4. 78 = 13x     x=6
  5. The area of a board game is 468 square inches.
     Its width is 18 inches. What is the length?
     26 inches




Course 1

Multiplication equations

  • 1.
    2-7 Multiplication Equations 2-7 Multiplication Equations Warm Up Problem of the Day Lesson Presentation Course 1 Course 1 Course 1
  • 2.
    2-7 Multiplication Equations Warm Up Divide. 72 1. 12 6 2. 65 13 5 40 3. 60 6 10 4. 10 4 130 5. 5 26 6. 91 13 7 Course 1
  • 3.
    2-7 Multiplication Equations Problem of the Day Katie’s little brother is building a tower with blocks. He adds 6 blocks and then removes 4 blocks. If he adds 8 more blocks, the tower will have twice as many blocks as when he started. How many blocks did he start with? 10 blocks Course 1
  • 4.
    2-7 Multiplication Equations Learn to solve whole-number multiplication equations. Course 1
  • 5.
    2-7 Multiplication Equations Division is the inverse of multiplication. To solve an equation that contains multiplication, use division to “undo” the multiplication. 4m = 32 Caution ! 4m = 32 4m means “4 × m.” 4 4 m=8 Course 1
  • 6.
    2-7 Multiplication Equations Additional Example 1A: Solving Multiplication Equations Solve the equation. Check your answer. 5p = 75 p is multiplied by 5. 5p = 75 Divide both sides by 5 to undo 5 5 the multiplication. p = 15 Check 5p = 75 ? 5(15)= 75 Substitute 15 for p in the equation. ? 75 = 75  15 is the solution. Course 1
  • 7.
    2-7 Multiplication Equations Additional Example 1B: Solving Multiplication Equations Solve the equation. Check your answer. 16 = 8r r is multiplied by 8. 16 = 8r Divide both sides by 8 to undo 8 8 the multiplication. 2= r Check 16 = 8r ? 16 = 8(2) Substitute 2 for r in the equation. ? 16 = 16  2 is the solution. Course 1
  • 8.
    2-7 Multiplication Equations Check It Out: Example 1A Solve the equation. Check your answer. 8a = 72 a is multiplied by 8. 8a = 72 Divide both sides by 8 to undo 8 8 the multiplication. x=9 Check 8a = 72 ? 8(9)= 72 Substitute 9 for a in the equation. ? 72 = 72  9 is the solution. Course 1
  • 9.
    2-7 Multiplication Equations Check It Out: Example 1B Solve the equation. Check your answer. 18 = 3w w is multiplied by 3. 18 = 3w Divide both sides by 3 to undo 3 3 the multiplication. 6=w Check 18 = 3w ? 18 = 3(6) Substitute 6 for w in the equation. ? 18 = 18  6 is the solution. Course 1
  • 10.
    2-7 Multiplication Equations Additional Example 2: Problem Solving Application The area of a rectangle is 56 square inches. Its length is 8 inches. What is its width? Course 1
  • 11.
    2-7 Multiplication Equations Additional Example 2 Continued 1 Understand the Problem The answer will be the width of the rectangle in inches. List the important information: • The area of the rectangle is 56 square inches. • The length of the rectangle is 8 inches. Draw a diagram to represent this information. 56 w 8 Course 1
  • 12.
    2-7 Multiplication Equations Additional Example 2 Continued 2 Make a Plan You can write and solve an equation using the formula for area. To find the area of a rectangle, multiply its length by its width. A = lw w 56 = 8w l Course 1
  • 13.
    2-7 Multiplication Equations Additional Example 2 Continued 3 Solve 56 = 8w w is multiplied by 8. 56 = 8w Divide both sides by 8 to undo 8 8 the multiplication. 7=w So the width of the rectangle is 7 inches. Course 1
  • 14.
    2-7 Multiplication Equations Additional Example 2 Continued 4 Look Back Arrange 56 identical squares in a rectangle. The length is 8, so line up the squares in rows of 8. You can make 7 rows of 8, so the width of the rectangle is 7. Course 1
  • 15.
    2-7 Multiplication Equations Check It Out: Example 2 The area of a rectangle is 48 square inches. Its width is 8 inches. What is its length? Course 1
  • 16.
    2-7 Multiplication Equations Check It Out: Example 2 1 Understand the Problem The answer will be the length of the rectangle in inches. List the important information: • The area of the rectangle is 48 square inches. • The width of the rectangle is 8 inches. Draw a diagram to represent this information. 48 8 l Course 1
  • 17.
    2-7 Multiplication Equations Check It Out: Example 2 Continued 2 Make a Plan You can write and solve an equation using the formula for area. To find the area of a rectangle, multiply its length by its width. A = lw w 48 = l8 l Course 1
  • 18.
    2-7 Multiplication Equations Check It Out: Example 2 Continued 3 Solve 48 = 8l l is multiplied by 8. 48 = 8l Divide both sides by 8 to undo 8 8 the multiplication. 6=l So the length of the rectangle is 6 inches. Course 1
  • 19.
    2-7 Multiplication Equations Check It Out: Example 2 Continued 4 Look Back Arrange 48 identical squares in a rectangle. The width is 8, so line up the squares in columns of 8. You can make 6 columns of 8, so the length of the rectangle is 6. Course 1
  • 20.
    2-7 Multiplication Equations Lesson Quiz 1. 10y = 300 y = 30 2. 2y = 82 y = 41 3. 63 = 9y y=7 4. 78 = 13x x=6 5. The area of a board game is 468 square inches. Its width is 18 inches. What is the length? 26 inches Course 1