FRACTIONS!

A slight review of all 4 operations

OBJECTIVE

Today we will review the basic operations, add, subtract, multiply and divide, of fractions!

NOOOOoooo!! Not fractions!!!

YES!!! FRACTIONS!!!!

Let’s start easy on ya;-)

Multiply Fractions

To multiply fractions, multiply the numerators and multiply the denominators.

Multiply. Write in simplest form.

12

13

X

12

X 13

1 x 12 x 3

=

Multiply the numerators

Multiply the denominators

=16

example

2 x 34

34

x2 = 21

34

x

Write 2 as

Multiply the numerators

21

Multiply the denominators

2 x 31 x 4

=

64

=

= 32

SIMPLIFY

YOUR TURN

35

12

x

3 x 15 x 2

= 310

1)

2) 23

x 4

2 x 43 x 1

23

41

x=

= = 83

Simplify Before Multiplying

If the numerator and denominator of either fraction have common factors, you can simplify before multiplying.

THIS WILL MAKE YOUR LIFE EASIER IN THE END!!

Multiply Mixed Numbers

Find x 4 12

25

Rewrite the mixed number as an improper fraction

= 225

254

12 X

225 = 1 x 22

2 x 5

= 115

//1

11

= 1 x 111 x 5

SIMPLIFY BEFORE MULTIPLYING TO MAKE LIFE EASIER!!

example

56

116

35

31 x

x 185

Write mixed #’s as improper fractions

11 x 18

6 x 5=

= 335

3

1

//

= 11 x 31 x 5

(take out common factor)

Dividing Fractions

To divide by a fraction, multiply by its reciprocal. Two numbers whose product is 1 are reciprocals.

23

32

The reciprocal of is

15

51

155 = xx = 1

8 ÷ 2 = 4 8 x = 412

reciprocals_____ _____

same results __________

Dividing 8 by 2 gives the same result as multiplying 8

by the reciprocal of 2, or 12

Dividing fractions is simple as pie; flip the

second number and multiply!

Divide by a Fraction

Find 34

12

÷

34

12

34

21

= x÷ Multiply by the reciprocal of ,which is 2.

12

= 34

21

x

=

3 x 24 x 1

32

=

Multiply

SIMPLIFY!!!

=

64

YOUR TURN!!

23

56

_..

56

32

x

= 5 x 36 x 2

= 1512

= 54

Multiply by the reciprocal

Divide by Mixed Numbers

15 12

1÷

15 ÷ 32

Rename 1 as an improper fraction12

15 23

x=

= x

Multiply by the reciprocal

151

23

= 15 x 21 x 3

= 303

= 10

Rewrite whole #’s over 1

YOUR TURN!!

6 12

57

3

x

÷

÷132

267

Rename the mixed #’s as improper fractions

132

726

Multiply by the reciprocal

726

132

x/

/1

2

Simplify before multiplying

1 x 72 x 2

74

=

=

=

=

=

AANNDDD NOOWWW…

The semi (but not really) harder part!

OH NOOOOOOO!!

ADDING AND SUBTRACTING FRACTIONS!!

Fractions that have the same denominators are called like fractions

Add and Subtract like fractions

1) add/subtract numerators

2) write the result over the denominator

3) SIMPLIFY!!!

EXAMPLE

59

29

+ = 5 + 29

= 79

9-110

110

910

810

- = = 45

=

YOUR TURN!!

89

29

8-29

69

=- = 23

=

58

78

5+78

128

32

+ = = =

1)

2)

Add and Subtract unlike fractions

1) Find the LCD

2) Rewrite your fractions using the LCD. (you will now have like fractions)

3) Add/subtract the like fractions

4) SIMPLIFY

12

1)

+ 16

2 = 1 x 26 = 2 x 3LCD= 2 x 3 = 6

12

2) ?6

=

=16

16

Find the LCD

Rewrite using the LCD= 3

6

3) 36

+ 16

= 3+16

46

23

4) SIMPLIFY

Add/Subtract=

EVALUATE

YOUR TURN!!

56

+ 78

4124

=

LCD = 24

56

= 2024

2124

78

=

2024

2124

+ = 20+2124

= 4124