Fundamentals of Mathematics, 2008a

307
5.4.1.1 Sample Set A
Find the following sums and dierences.
Example 5.14
8 3 5 + 5 1 4
. Convert each mixed number to an improper fraction.
8 3 5 = 5·8+3
5
= 40+3
5
= 43 5
5 1 4 = 4·5+1
4
= 20+1
4
= 21 4 Now add the improper fractions 43 5 and 21 4 .
43
5 + 21
4
The LCD = 20.
43
5 + 21 4
= 43·4
20 + 21·5
20
= 172
20 + 105
20
172+105
=
20
277
=
20
Convert this improper fraction to a mixed number.
= 13 17
20
Thus, 8 3 5 + 5 1 17
4
= 13
20 .
Example 5.15
3 1 8 − 5 6
. Convert the mixed number to an improper fraction.
3 1 8 = 3·8+1
8
= 24+1
8
= 25 8
25
8 − 5 6
The LCD = 24.
25
8 − 5 6
= 25·3
24 − 5·4
24
75
=
24 − 20
24
75−20
=
24
55
=
24
Convert his improper fraction to a mixed number.
= 2 7 24
Thus, 3 1 8 − 5 6 = 2 7
24 .
5.4.1.2 Practice Set A
Find the following sums and dierences.
Exercise 5.4.1 (Solution on p. 331.)
1 5 9 + 3 2 9
Exercise 5.4.2 (Solution on p. 331.)
10 3 4 − 2 1 2
Exercise 5.4.3 (Solution on p. 331.)
2 7 8 + 5 1 4
Exercise 5.4.4 (Solution on p. 331.)
8 3 5 − 3
10
Exercise 5.4.5 (Solution on p. 331.)
16 + 2 9
16
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