3x^2 - 12 = 3(x^2 - 4) = 3( x - 2)(x + 2)
16x - 4x^3 = 4x(4 - x^2) = 4( 2 - x)(2 + x)
32a^4b - 2a^2b = 2a^2b( 16a^2 - 1) = 2a^2b(4a - 1)(4a + 1)
2m^2 + 2n^2 - 4mn = 2m^2 - 4mn + 2n^2= 2(m^2 - 2mn + n^2)=
= 2( m - n)^2 = 2( m - n)(m - n)
8p^2 - 16p + 8 = 8(p^2 - 2p + 1) = 8(p - 1)^2 = 8(p - 1)(p - 1)
(x^2 + 2x)^2 - 1^2 = (x^2 + 2x - 1)(x^2 + 2x + 1)
81 - (y^2 + 6y)^2 = ( 9 - y^2 - 6y)(9 + y^2 + 6y)