How do you multiply binomials $(a+b)(a-b)$ ?

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Answer 1 · 2015-04-06T21:36:25

This is a special pattern called the difference of squares.

If we FOILed this out:
$(a+b)(a-b)$
$(a^2-ab+ab-b^2)$

Notice how the two middle terms cancel. You now have the important pattern:
$(a+b)(a-b) = (a^2-b^2)$

How do you multiply binomials (a+b)(a-b)(a+b)(a-b)?