Adding Fractions
1/4 + 2/3 =
3/12 + 8/12 = 11/12
4/5 - 1/3 =
12/15 - 5/15 = 7/15
1/2 and 3/5
LCD = 10
If the denominators are the same for two fractions, do we have to find the least common denominator (LCD)?
No, we can add or subtract the fractions as is.
What are equivalent fractions?
Fractions that have the same value but different numerators and denominators.
True or False:
4/9 + 1/6 = 10/18
False.
8/18 + 3/18 = 11/18
True or False:
4/3 - 2/7 = 1 1/21
True.
28/21 - 6/21 =
22/21 OR 1 1/21
5/12 and 2/9
LCD: 36
What is the first thing you do when you are adding or subtracting fractions with unlike denominators?
Find the least common denominator (LCD) for all of the fractions.
What fraction is equivalent to 2/9?
Answers will vary: 1/3, 4/18, 6/27
11/12 + 7/15 =
55/60 + 28/60 =
83/60 OR 1 23/60
11/12 - 7/15 =
55/60 - 28/60 =
27/60
reduced form: 9/20
1/6 and 4/21
LCD: 42
Add and subtract 3/4 and 1/5
15/20 and 4/20
Addition = 19/20
Subtraction= 11/20
What strategy can you use to find an equivalent fraction?
Multiply or divide the fraction by a whole (multiply or divide the numerator and denominator by the same number).
1/4 + 3/7
7/28 + 12/28
19/28
6/7 - 1/2 =
12/14 - 7/14=
5/14
9/10, 5/6, and 2/3
LCD: 30
What is an improper fraction? What is a mixed number?
1) A fraction that is greater than a whole written with a larger numerator than the denominator.
2) A fraction that is greater than a whole written as the number of wholes and the part of the whole.
Write a fraction that is equivalent to 12/16?
Answers will vary: 3/4, 24/32, 48, 64
1/2 + 1/3 + 1/4 =
6/12 + 4/12 + 3/12 =
13/12 OR 1 1/12
5/6 - 1/4 - 1/3 =
10/12 - 3/12 - 4/12=
3/12
11/14, 17/42, and 2/3
LCD: 42
What are 2 ways you can get two fractions with unlike denominators to have the same denominator?
1) Find the least common denominator (LCD)
2) Multiply the two denominators by one another
Using division, find an equivalent fraction to 24/36.
Answers may vary: 6/9, 8/12, 2/18, 4/6