Subtracting FractionsFind each difference, and write it in lowest terms.
(a)
Subtract numerators.
Keep the same denominator.Write in lowest terms
and as a mixed number.(b)
and so
the LCD isWrite the equivalent fractions.Subtract. The answer is in
lowest terms.(c)
Since and there are no common factors.
The LCD is
Find a common denominator.Write the equivalent fractions.Subtract numerators.
Keep the common denominator.(d)
Method 1
Write each mixed number as an
improper fraction.= Subtract. Write as a mixed number.
11
4
, or 2
3
4
=
18
4
-
7
4
4
1
2
- 1
3
4
=
9
2
-
7
4
4
1
2
- 1
3
4
=
323
1440
=
675
1440
-
352
1440
15
32
-
11
45
=
15 # 45
32 # 45-
11 # 32
45 # 3232 # 45 =1440.
32 = 2 # 2 # 2 # 2 # 2 45 = 3 # 3 #5,
15
32
-
11
45
=
11
90
=
35
90
-
24
90
2 # 3 # 3 # 5 =90.
18 = 2 # 3 # 3 15 = 3 #5,
7
18
-
4
15
=
7 # 5
2 # 3 # 3 # 5-
4 # 2 # 3
2 # 3 # 3 # 5=
3
2
, or 1
1
2
=
12
8
15
8
-
3
8
=
15 - 3
8
EXAMPLE 7
8 CHAPTER 1 The Real Number System
Think:^92 ##^22 =^184NOW TRY
EXERCISE 7
Find each difference, and
write it in lowest terms.
(a) (b) 4
1
3
- 2
5
6
5
11
-
2
9
NOW TRY ANSWERS
- (a)^2399 (b) 23 , or 1 (^12)
Method 2
or NOW TRY
11
4
2
3
4
,
- 1
3
4
= 1
3
4
= 1
3
4
4 4 42 = 3 + 1 +^24 = 3 +^44 +^24 = (^3 64)
1
2
= 4
2
4
= 3
6
4
Find a common denominator.
The LCD is 4.http://www.ebook777.com
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