1) 3(a^2 - b^2) = 3( a - b)(a + b)
2) 5( x^2 - 1) = 5( x - 1)(x + 1)
3) x( x^2 - 9) = x( x - 3)(x + 3)
4) 3( a^2 - 2a + 1) = 3( a - 1)(a - 1)
5) - 2( a^2 + 2ab + b^2) = - 2( a + b)(a + b)
6) 8( x^2 + 2xy + y^2) = 8( x + y)(x + y)
7) y( 4x^2 - 4x - 1)