7. Addition and Subtraction of Fractions

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

 

Example 1:

math expression

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

math expression

Subtraction works in the same way...

Example 2:

math expression

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

math expression

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

 

Example 1:

math expression

The lowest common denominator here will be 6y4.

So we have:

math expression

We can write this as:

math expression

 

Example 2:

math expression

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

math expression

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

math expression

We would normally write this as:

math expression

 

Exercises. Simplify:

(1) math expression


Answer

(2) math expression


Answer

(3) math expression


Answer



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