Question
Factor polynomial $$ 9x^{2}-y^{2} $$
Answer
$$ 9x^{2}-y^{2} = (3x+y)(3x-y) $$
Explanation
Rewrite $ 9x^2-y^2 $ as:
$$ \color{blue}{ 9x^2-y^2 = (3x)^2 - (y)^2 } $$Now we can apply the difference of squares formula.
$$ I^2 - II^2 = (I - II)(I + II) $$After putting $ I = 3x $ and $ II = y $ , we have:
$$ 9x^2-y^2 = (3x)^2 - (y)^2 = ( 3x-y ) ( 3x+y ) $$This page was created using
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