The correct option is C (3x−9)(9x2+7y2−15xy)
27x3−54x2y+36xy2−7y3
Using,
(a−b)3=a3−b3−3a2b+3ab2
=(3x)3−3(3x)2(2y)+3(3x)(2y)2−(2y)3+y3
=(3x−2y)3+y3
Using,
(a3+b3)=(a+b)(a2−ab+b2)
=(3x−2y+y)[(3x−2y)2−(3x−2y)(y)+(y)2]
=(3x−y)(9x2+4y2−12xy−3xy+2y2+y2)
=(3x−y)(9x2+7y2−15xy)