| GOOD NEWS!!! | ||||
| This is our last method for finding common denominators. | ||||
| Start with something like this ... | ||||
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| STEP 1: | ||||
| Break up the denominators into prime factors ... | ||||
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| STEP 2: | ||||
| List the denominator (Bottom part) prime factors. | ||||
| Write a number the most times it appears in EITHER fraction. | ||||
| This is the common denominator. | ||||
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2 x 2 x 2 x 3 |
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| STEP 3: | ||||
| Make fractions equal to 1 to multiply each fraction in the problem by. | ||||
| The number you build is made up of the common denominator factors | ||||
| that ARE NOT in that denominator. | ||||
| In the first fraction, | ||||
| the denominator is made up of 2 x 3. | ||||
| The common denominator | ||||
| is made up of 2 x 2 x 2 x 3 | ||||
| The missing numbers are 2 x 2, | ||||
| so that is what we use in our multiplying fraction. | ||||
| Remember that the multiplying fraction must equal 1. | ||||
| That means we use the same thing on the top and bottom | ||||
| of the multiplying fraction. | ||||
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| You can multiply out the numbers in each fraction first | ||||
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if you want to. |
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| Then multiply the fractions ... | ||||
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| In the second fraction, | ||||
| the denominator is made up of 2 x 2 x 2. | ||||
| The common denominator | ||||
| is made up of 2 x 2 x 2 x 3 | ||||
| The missing number is 3, | ||||
| so that is what we use in our multiplying fraction. | ||||
| Remember that the multiplying fraction must equal 1. | ||||
| That means we use the same thing on the top and bottom | ||||
| of the multiplying fraction. | ||||
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| STEP 4: | ||||
| Now we have a common denominator so we can subtract. | ||||
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| STEP 5: | ||||
| Simplify if possible ... | ||||
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|
copyright 2005 Bruce Kirkpatrick |
