Algebra Demystified 2nd Ed

Chapter 1 FraCtions 13

3.^1
6

1

6

+=

4.^5
12

1

12

−=

5. 112 += 119

SOLUTIONS

1.^4
7

1

7

41

7

3

7

−=− =

2.^1
5

3

5

13

5

4

5

+=+ =

3.^1
6

1

6

11

6

2

6

1

3

+=+ ==

4.^5
12

1

12

51

12

4

12

1

3

−=− ==

5. 112 += 119 2911 + == 1111 1

Adding and Subtracting Fractions with Unlike Denominators

If we need to find the sum or difference of two fractions having different

denominators, then we must rewrite one or both fractions so that they have the

same denominator. Let us use the pie model to find the sum^1

4

1

3

+.

If we divide the pie into 34 ×= 12 equal pieces, we see that^14 is the same as

123 and^13 is the same as 124.

Now that we have these fractions written so that they have the same deno-

minator, we can add them:^1

4

1

3

3

12

4

12

34

12

7

+= += 12

+ =.

1

4

1

3

FIGURE 1-8

4

12

3

12

FIGURE 1-9

✔SOLUTIONS