Factoring strategy selection involves interpreting an algebraic expression as a product and examining its structure to determine whether to first extract a greatest common factor, use a special-product pattern such as a difference of squares, factor a quadratic trinomial, or apply grouping for suitable four-term expressions. The reasoning includes checking that the proposed factors reproduce the original expression through multiplication; multivariable and higher-degree methods beyond these standard quadratic and polynomial forms are not included.
To choose a factoring strategy, first look at the structure of the expression.
Step 1: Find the GCF.
The terms are and . Their greatest common factor is .
Factor out :
Step 2: Examine what remains.
The expression inside the parentheses, , has two terms and is a difference of squares:
Use the pattern :
Therefore,
Step 3: Check by multiplying.
First multiply the conjugate factors:
Then multiply by :
This matches the original expression, so the factoring is correct. The key strategy was to take out the GCF first, then recognize the difference-of-squares pattern.
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