Factorise:
2x3+54y3−4x−12y
= 2(x3 + 27y3 - 2x - 6y)
= 2{[(x)3+(3y)3] - 2(x + 3y)}
[Using identity (a3 + b3) = (a + b)(a2 - ab + b2)]
=2{[(x + 3y)(x2 - 3xy + 9y2)] - 2(x + 3y)}
=2(x + 3y)(x2 - 3xy + 9y2 - 2)