2-8 Division Equations

Warm Up

Lesson Presentation

Problem of the Day

Lesson Quizzes

2-8 Division Equations

Warm UpSolve.

1. 5x = 20

2. 7n = 84

3. 18 = y – 4

4. 21 = n + 3

x = 4

n = 12

y = 22

n = 18

2-8 Division Equations

Problem of the Day

If 11 is 4 less than 3 times a number, what is the number?5

2-8 Division Equations

Learn to solve whole-number division equations.

2-8 Division Equations

Recall that multiplication and division are inverse operations. If an equation contains division, solve it by multiplying on both sides to “undo” the division.

2-8 Division Equations

x = 35

Multiply both sides by 7 to undo the division.

Substitute 35 for x in the equation.

Solve the equation. Check your answer.

35 is the solution.5 = 5?

Additional Example 1A: Solving Division Equations

x7

= 5

x is divided by 7. x7

= 5

7 x7

= 7 5

Check x7

= 5 357

= 5?

2-8 Division Equations

78 = p

Multiply both sides by 6 to undo the division.

Substitute 78 for p in the equation.

Solve the equation. Check your answer.

78 is the solution.13 = 13?

Additional Example 1B: Solving Division Equations

p6

13 =

6 p6

6 13 =

p is divided by 6. p6

13 =

Check p6

13 =

? 786

13 =

2-8 Division Equations

x = 18

Multiply both sides by 2 to undo the division.

Substitute 18 for x in the equation.

Solve the equation. Check your answer.

18 is the solution.9 = 9?

Check It Out: Example 1A

x2

= 9

x is divided by 2. x2

= 9

2 x2

= 2 9

Check x2

= 9 182

= 9?

2-8 Division Equations

288 = p

Multiply both sides by 4 to undo the division.

Substitute 288 for p in the equation.

Solve the equation. Check your answer.

288 is the solution.72 = 72?

Check It Out: Example 1B

p4

72 =

4 p4

4 72 =

p is divided by 4. p4

72 =

Check p4

72 =

? 2884

72 =

2-8 Division Equations

At Elk Meadows Park an aspen tree is one-third the height of a pine tree.

Additional Example 2: Application

height of aspen = height of pine3

The aspen tree is 14 feet tall. How tall is the pine tree?Let h represent the height of the pine tree.

42 = h

Multiply both sides by 3 to undo the division.

3 h3

3 14 =

Substitute 14 for height of aspen. h is divided by 3.

h3

14 =

The pine tree is 42 feet tall.

2-8 Division Equations

Check It Out: Example 2

Let w represent her father’s weight.

190 = w

Multiply both sides by 2 to undo the division.

2 w2

2 95 =

Substitute 95 for Jamie’s weight. w is divided by 2.

w2

95 =

Jamie’s father weighs 190 pounds.

Jamie weighs one-half as much as her father.

Jamie’s weight = father’s weight 2

Jamie weighs 95 pounds. How many pounds does her father weigh?

2-8 Division Equations

Standard Lesson Quiz

Lesson Quizzes

Lesson Quiz for Student Response Systems

2-8 Division Equations

1. = 7

2. 8 =

3. = 11

4. = 7

Lesson Quiz

5. The area of Sherry’s flower garden is one-fourth the area of her vegetable garden. Thearea of the flower garden is 17 square feet. Let xrepresent the area of her vegetable garden. Findthe area of her vegetable garden.

x = 70

x = 32

x = 99

x = 105

68 square feet

x 4

x 9

Solve each equation. Check your answers.

x 10

x 15

2-8 Division Equations

1. Solve the equation = 15.

A. x = 3

B. x = 5

C. x = 20

D. x = 75

Lesson Quiz for Student Response Systems

x 5

2-8 Division Equations

2. Solve the equation 14 = .

A. x = 21

B. x = 28

C. x = 98

D. x = 121

Lesson Quiz for Student Response Systems

x 7

2-8 Division Equations

3. Solve the equation = 42.

A. x = 40

B. x = 44

C. x = 84

D. x = 104

Lesson Quiz for Student Response Systems

x 2

2-8 Division Equations

4. Solve the equation = 30.

A. y = 99

B. y = 90

C. y = 33

D. y = 27

Lesson Quiz for Student Response Systems

y 3

2-8 Division Equations

5. The area of Linda’s rose garden is one-ninth the area of her lawn. The area of the rose garden is 15 square feet. Let x represent the area of her lawn. Identify the area of her lawn.

A. 9 square feet

B. 24 square feet

C. 135 square feet

D. 150 square feet

Lesson Quiz for Student Response Systems