How do you factor $4b^2 - 9$ ?

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Answer 1 · 2015-11-14T03:06:42

$4b^2 - 9 = (2b + 3)(2b-3)$

The difference of squares formula states that
$a^2 - b^2 = (a+b)(a-b)$
(this may be easily verified by expanding the right hand side of the equation)

$4b^2 = (2b)^2$
$9 = 3^2$

Thus, by the difference of squares formula:

$4b^2 - 9 = (2b)^2 - 3^2 = (2b + 3)(2b-3)$

How do you factor 4b^2 - 94b^2 - 9?