Subtracting Fractions with Unlike Denominators:

Remember that given a fraction, such as , the top number is the numerator (namely 1) and the bottom number is the denominator (namely 2) 

Example 1:

Whenever you subtract fractions with unlike denominators, you need to make the denominators equal to each other by finding the least common denominator.  In this example, you need to multiplyby 4 to get .  Next, you need to multiply the second equation  by 5 to get .  Notice that both fractions have 20 as a common denominator.  Subtract in the same manner as with the unit Subtracting fractions with like denominators.

 

 

 

Example 2:

Whenever you subtract fractions with unlike denominators, you need to make the denominators equal to each other by finding the least common denominator.   In this example, first find a common denominator.  Here, you multiply  by  to get .  Then you multiply the second fraction by  to get .   Note that both fractions have 24 as a denominator.  Subtract in the same manner as with the unit Subtracting fractions with like denominators.

 

 

 

Try this problem:

 

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When you are ready, click here to go to the subtraction of fractions with unlike denominators practice page.  You may need some scratch paper to do the practice.