Adding 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 add 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 multiply  by 5 to get .  Next, you need to multiply the second equation by 4 to get . Note that both fractions now have a common denominator.  Add in the same manner as with the unit Adding fractions with like denominators.

 

Example 2:

Whenever you add fractions with unlike denominators, you must make the denominators of the same value.  In this example, the easiest approach is to multiply 8 x 3 to get 24.  Here, you multiply by 3 to get .  Then you multiply the second equation  by 8 to get .  Note that both addends have 24 as a denominator.  Add in the same manner as with the unit Adding fractions with like denominators.

 

 

Try this problem:

 


 

 

 

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