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Chapter Contents

• Factoring and Fractions
• 1. Special Products
• 2. Common Factor and Difference of Squares
• 3. Factoring Trinomials
• 4. The Sum and Difference of Cubes
• 5. Equivalent Fractions
• 6. Multiplication and Division of Fractions
• 7. Addition and Subtraction of Fractions
• 8. Equations Involving Fractions

• Comments, Questions?

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7. Addition and Subtraction of Fractions

Recall that to add or subtract fractions, we need to have the same denominator.

 

Example 1:

Here, the lowest common denominator which we can use is 15. So we have:

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Subtraction works in the same way...

Example 2:

Our lowest common denominator this time is 14. So we have:

When we have algebra using fractions, use the same rules.

 

Example 1:

The lowest common denominator here will be 6y⁴.

So we have:

We can write this as:

 

Example 2:

We factor the first denominator to get an idea of what to do:

We can see now that if we multiply the second fraction by 2x², we will have a common denominator:

We would normally write this as:

 

Exercises. Simplify:

(1)

Answer

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(2)

Answer

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(3)

Answer