2 7 Multiplication Equations Warm Up Problem of

2 -7 Multiplication Equations Warm Up Problem of the Day Lesson Presentation Lesson Quizzes

2 -7 Multiplication Equations Warm Up Divide. 72 1. 12 6 13 2. 65 5 3. 60 6 10 40 4. 10 130 5. 5 26 6. 91 13 7 4

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

2 -7 Multiplication Equations Learn to solve whole-number multiplication equations.

2 -7 Multiplication Equations Multiplication and division are inverse operations. To solve an equation that contains multiplication, use division to “undo” the multiplication. 4 m = 32 4 4 m=8 Caution ! 4 m means “ 4 m. ”

2 -7 Multiplication Equations Additional Example 1 A: Solving Multiplication Equations Solve the equation. Check your answer. 5 p = 75 p is multiplied by 5. 5 p = 75 5 5 Divide both sides by 5 to undo the multiplication. p = 15 Check 5 p = 75 ? 5(15)= 75 ? 75 = 75 Substitute 15 for p in the equation. 15 is the solution.

2 -7 Multiplication Equations Additional Example 1 B: Solving Multiplication Equations Solve the equation. Check your answer. 16 = 8 2= Check 8 r 8 r 8 r 16 = 8 r ? 16 = 8(2) ? 16 = 16 r is multiplied by 8. Divide both sides by 8 to undo the multiplication. Substitute 2 for r in the equation. 2 is the solution.

2 -7 Multiplication Equations Check It Out: Example 1 A Solve the equation. Check your answer. 8 a = 72 a is multiplied by 8. 8 a = 72 8 8 a=9 Divide both sides by 8 to undo the multiplication. 8 a = 72 ? 8(9)= 72 ? 72 = 72 Check Substitute 9 for a in the equation. 9 is the solution.

2 -7 Multiplication Equations Check It Out: Example 1 B Solve the equation. Check your answer. w is multiplied by 3. 18 = 3 w Check 18 = 3 w 3 3 6=w Divide both sides by 3 to undo the multiplication. 18 = 3 w ? 18 = 3(6) ? 18 = 18 Substitute 6 for w in the equation. 6 is the solution.

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?

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 8 w

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 56 = 8 w w l

2 -7 Multiplication Equations Additional Example 2 Continued 3 Solve 56 = 8 w 8 8 7=w w is multiplied by 8. Divide both sides by 8 to undo the multiplication. So the width of the rectangle is 7 inches.

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.

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?

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 l 8

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 48 = l 8 w l

2 -7 Multiplication Equations Check It Out: Example 2 Continued 3 Solve 48 = 8 l 8 8 6=l l is multiplied by 8. Divide both sides by 8 to undo the multiplication. So the length of the rectangle is 6 inches.

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.

2 -7 Multiplication Equations Lesson Quizzes Standard Lesson Quiz for Student Response Systems

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

2 -7 Multiplication Equations Lesson Quiz for Student Response Systems 1. Solve the equation 2 x = 88. A. x = 90 B. x = 86 C. x = 48 D. x = 44

2 -7 Multiplication Equations Lesson Quiz for Student Response Systems 2. Solve the equation 3 y = 75. A. y = 25 B. y = 35 C. y = 75 D. y = 78

2 -7 Multiplication Equations Lesson Quiz for Student Response Systems 3. Solve the equation 72 = 8 x. A. x = 80 B. x = 64 C. x = 9 D. x = 8

2 -7 Multiplication Equations Lesson Quiz for Student Response Systems 4. Solve the equation 91 = 7 y. A. y = 13 B. y = 17 C. y = 73 D. y = 84

2 -7 Multiplication Equations Lesson Quiz for Student Response Systems 5. The area of Carl’s rectangular flower garden is 192 square feet. Its length is 16 feet. What is the width? A. 8 feet B. 12 feet C. 14 feet D. 16 feet