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4y^2 - 81

 Sep 15, 2017
 #1
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We can factor this as a "difference of squares."  Remember that  a2 - b2  =  (a + b)(a - b) . So....

 

4y2  -  81     =     (2y)2 - 92     =     ( 2y + 9 )( 2y - 9 )

 Sep 15, 2017

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