Subtracting Fractions
To subtract fractions, you need to find a common denominator first, then subtract the numerators while keeping the denominator the same.
When subtracting fractions, follow these steps:
- Find the least common multiple (LCM) of the denominators - this will be your common denominator
- Convert each fraction to an equivalent fraction with the common denominator
- Subtract the numerators while keeping the denominator the same
- Simplify the result if possible
Let's look at some examples:
Example 1: Subtract 3/4 - 1/6
- First, find the least common multiple of 4 and 6, which is 12.
- Convert both fractions to equivalent fractions with denominator 12:
- 3/4 = (3 × 3)/(4 × 3) = 9/12
- 1/6 = (1 × 2)/(6 × 2) = 2/12
- Now subtract the numerators: 9/12 - 2/12 = 7/12
- Since 7 and 12 have no common factors, 7/12 is already in simplest form.
Example 2: Subtract 5/8 - 1/4
- The LCM of 8 and 4 is 8.
- 5/8 remains as 5/8
- 1/4 = (1 × 2)/(4 × 2) = 2/8
- Now subtract: 5/8 - 2/8 = 3/8
Example 3: Subtract 4 2/3 - 1 5/6
- For mixed numbers, first convert them to improper fractions:
-
4 2/3 = (4 × 3 + 2)/3 = 14/3
1 5/6 = (1 × 6 + 5)/6 = 11/6
- Now find the LCM of 3 and 6, which is 6:
- 14/3 = (14 × 2)/(3 × 2) = 28/6
- 11/6 remains as 11/6
- Subtract: 28/6 - 11/6 = 17/6
- Convert back to a mixed number: 17/6 = 2 5/6
- So 4 2/3 - 1 5/6 = 2 5/6
Remember that when subtracting fractions with different denominators, the key is to find a common denominator first, then perform the subtraction.