Question: how do you factor 9x^2-1?
Answer: Rewrite 9x2 9 x 2 as (3x)2 ( 3 x ) 2 . Rewrite 1 as 12 . Since both terms are perfect squares, factor using the difference of squares formula, a2−b2=(a+b)(a−b) a 2 - b 2 = ( a + b ) ( a - b ) where a=3x a = 3 x and b=1 .