am^2 - an^2 = a(m^2 - n^2) = a(m + n)(m - n)
9p^2 - 9 = 9(p^2 - 1) = 9(p + 1)(p - 1)
75 - 27c^2 = 3(25 - 9c^2) = 3(5 + 3c)(5 - 3c)
am^2 - an^2 = a(m^2 - n^2) = a(m + n)(m - n)
9p^2 - 9 = 9(p^2 - 1) = 9(p + 1)(p - 1)
75 - 27c^2 = 3(25 - 9c^2) = 3(5 + 3c)(5 - 3c)