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Factoring Four or More Terms by Grouping

When four or more terms come together to form an expression, you always look for a greatest common factor first. If you can’t find a factor common to all the terms at the same time, your other option is grouping. To group, you take the terms two at a time and look for common factors for each of the pairs on an individual basis. After factoring, you see if the new groupings have a common factor.

The best way to explain this is to demonstrate the factoring by grouping on a few examples.

Example 1:

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The four terms

image1.png

don’t have a common factor. However, the first two terms have a common factor of

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and the last two terms have a common factor of 3:

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Notice that you now have two terms, not four, and they both have the factor (x – 4). Now, factoring (x – 4) out of each term, you have

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Factoring by grouping only works if a new common factor appears — the exact same one in each term.

Example 2:

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The six terms

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don’t have a common factor, but, taking them two at a time, you can pull out the factors

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Factoring by grouping, you get the following:

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The three new terms have a common factor of (x – 2), so the factorization becomes

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The trinomial that you create lends itself to the unFOIL factoring method:

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Factored, and ready to go!

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