How do you multiply $(3x - 5) ( 3x + 5)$ ?

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Answer 1 · 2017-03-10T20:03:38

$9x^2-25$

$(a+b)(a-b) = a^2-b^2$

substitute $a$ with $3x$ and $b$ with $5$ :

$(3x+5)(3x-5) = (3x)^2 - 5^2$

$=9x^2 - 25$

$therefore (3x+5)(3x-5) = 9x^2 - 25$

How do you multiply (3x - 5) ( 3x + 5)(3x - 5) ( 3x + 5)?