Post on 17-Jan-2016
transcript
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