2.8 Using reciprocals to divide fractions

2.8 Using reciprocals to divide fractions

BIM II

​page 80 and 81

​Vocabulary

​DIVISION FRACTION PROPERTY

​A rule for dividing that says division by a fraction is the same as multiplication by the reciprocal of the fraction. Another name for this property is the "invert and multiply rule" for example

​Both are correct.

When you multiply by 1/2 , you take 1 of 2 equal groups. You do the same thing when you divide by 2. You get an answer of 10 in both.

​10 ÷ 3

​

​

​ 10/3 or 3 1/3 gallons

​10 ÷ 11

​10/11 gallons

​10 * 1/4

10 * 1/11

​3

​8/15

2

​I can change 3 3/8 to 27/8 and multiply by 4/5, the reciprocal of 5/4.

​16/30 or 8/15

12/4 or 3

​6/12 or 1/2

​1/2

​12/6 or 2

​3/4 ÷ 1/8

​6 batches

​2/3 * 5/6

​3/7 * 2/3

​3/4 * 8

​12/15

​6/21

​ANSWER THE PAGE 82 MATH BOXES

Fill in the Blank

Write the reciprocal of each fraction by switching the top and bottom numbers.

$$\frac{3}{8}=$$  

Fill in the Blank

Write the reciprocal of each fraction by switching the top and bottom numbers.

$$\frac{8}{12}=$$  

Fill in the Blank

Write the reciprocal of each fraction by switching the top and bottom numbers.

$$\frac{1}{5}=$$  

Fill in the Blank

Write the reciprocal of each fraction by switching the top and bottom numbers.

$$\frac{6}{15}=$$  

Fill in the Blank

Write the reciprocal of each fraction by switching the top and bottom numbers.

$$\frac{8}{16}=$$  

Multiple Select

$$\frac{1}{4}\div\frac{19}{12}$$

• 19/48

• 12/76

• 6/38

• 3/19

Multiple Choice

$$\frac{2}{5}\div\frac{7}{9}$$  

• 18/35

• 35/18

• 14/45

• 7/9

Multiple Select

$$\frac{4}{5}\times\frac{5}{6}$$  

• 20/30

• 2/3

• 24/25

• 25/24

Multiple Select

$$\frac{5}{3}\times\frac{3}{8}$$  

• 9/40

• 5/8

• 15/24

• 40/9

Multiple Choice

$$\frac{5}{3}\div\frac{3}{8}$$  

• 15/24

• 15/40

• 9/40

• 40/9

​REMEMBER TO UPLOAD YOUR MATH JOURNAL PAGES

​80,81,82

​

​HOMEWORK> HL 2.8