How do you factor the expression $9x² - 1$ ?

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Answer 1 · 2015-12-06T12:59:59

$color(blue)((3x+1)(3x-1)$

$9x^2-1$

The above expression can be written as
$(3x)^2 - 1^2$

As per property
$color(blue)(a^2-b^2=(a+b)(a-b)$

So for the given expression
$color(blue)(a=3x$
$color(blue)(b=1$

$(3x)^2 - 1^2= color(blue)((3x+1)(3x-1)$

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