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Lesson

A complex fraction is one whose numerator or denominator, or both, contains either:
                (i)  one or more fractions or, 
                (ii) powers with negative exponents. 

For example,

          and       

are complex fractions.

There are two methods of simplifying complex fractions.

Method 1: Express the fraction as a quotient using the sign ¸

Method 2: Multiply the numerator and denominator by the LCD of all the fractions
                  within the numerator and denominator. 

Example 1

Simplify:  

Solution (Method 1)

Solution (Method 2)

Example 2

Simplify:  

Solution (Method 1)

Solution (Method 2)

Example 3

Simplify:  

Solution (Method 1)

Solution (Method 2)

Example 4

Simplify: 

Solution (Method 1)

Solution (Method 2)

Although each of the examples above are solved by both methods, it is left to you to pick the method that you follow best or that best suits a given complex fraction.

We can apply the concepts and operations associated with rational expressions to various problem solving situations similar to that presented in Question 7 on the pre-test.

In order to answer some of these questions you will need to recall the formulas for areas and volumes of various geometric figures.

Example 1

A sphere of radius x is to be fit into a cubical container for shipping. If the sphere just touches the sides of the container in which it is placed, what fraction of the volume of the container is not used by the sphere?

Solution
Since the radius of the sphere is x, its diameter is 2x, and thus the cube is 2x units on a side.

The volume of the cube = (2x)(2x)(2x) = 8x3

The volume of the sphere =

Volume not used = 8x3 -

Activity

Simplify each of the complex fractions in exercises 1 to 12.

1.                              2.                             3. 

4.              5.                      6. 

7.                 8.                  9. 

10.           11.           12. 

13. What fraction of the rectangle ABCD is shaded?

Answers

Test Yourself

Simplify each of the complex fractions in exercises 1 to 6.

1.                       2.                           3. 

4.                      5.                      6. 

7.  If the two balls pictured in the container below just touch the sides of the  container, what fraction of the volume of the container is unused by the two balls?  (Hint: let the radius of the balls be r).

Answers