When we subtract fractions that have the same, or like denominators, we subtract only the numerators. The denominators stay the same.
Example:
Subtracting Fractions With Unlike Denominators
To subtract fractions with unlike denominators, we need to change the fractions to equivalent farctions with common, or like, denominators before we find the difference.
First, we would need to find the least common denominator (LCD), which is the LCM of the denominators.
Next, we write equivalent fractions using the least common denominator. Then, we proceed to subtract as before.
Example:
Evaluate
Solution:
Step 1 : Find the LCD or LCM of 2 and 5
Multiples of 2: 2, 4, 6, 8, 10, 12
Multiples of 5: 5, 10, 15
The LCD or the Least Common Multiple of 2 and 5 is 10
Step 2 : Write both fractions as equivalent fractions with a common denominator of 10.
Step 3: Subtract the 2 equivalent fractions.
The following video will give more examples of adding and subtracting fractions.