Fundamentals of Mathematics, 2008a

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CHAPTER 5. ADDITION AND SUBTRACTION OF FRACTIONS,
COMPARING FRACTIONS, AND COMPLEX FRACTIONS
Example 5.7
. The denominators are the same. Subtract the numerators. Place the dierence over 6.
8
6 − 2 6
8
6 − 2 6 = 8−2
6
= 6 6 = 1
Example 5.8
. The denominators are the same. Subtract numerators and place the dierence over 9.
16
9 − 2 9
16
9 − 2 9 = 16−2
9
= 14 9
Example 5.9
To see what happens if we mistakenly subtract the denominators, let's consider
7
15 − 4 15 = 7−4
15−15 = 3 0
We get division by zero, which is undened. We do not subtract denominators.
5.2.3.2 Practice Set B
Find the following dierences.
Exercise 5.2.6 (Solution on p. 329.)
10
13 − 8
13
Exercise 5.2.7 (Solution on p. 329.)
5
12 − 1
12
Exercise 5.2.8 (Solution on p. 329.)
1
2 − 1 2
Exercise 5.2.9 (Solution on p. 329.)
26
10 − 14
10
Exercise 5.2.10 (Solution on p. 329.)
Show why subtracting both the numerators and the denominators is in error by performing the
subtraction 5 9 − 2 9 .
5.2.4 Exercises
For the following problems, nd the sums and dierences. Be sure to reduce.
Exercise 5.2.11 (Solution on p. 329.)
3
8 + 2 8
Exercise 5.2.12
1
6 + 2 6
Exercise 5.2.13 (Solution on p. 329.)
9
10 + 1
10
Exercise 5.2.14
3
11 + 4
11
Exercise 5.2.15 (Solution on p. 329.)
9
15 + 4
15
Exercise 5.2.16
3
10 + 2
10
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