928. Представьте в виде произведения:

a) $$a^3b^3 - 1 = (ab)^3 - 1^3 = (ab-1)(a^2b^2+ab+1)$$

б) $$1 + x^3y^3 = 1^3 + (xy)^3 = (1+xy)(1-xy+x^2y^2)$$

в) $$8 - a^3c^3 = 2^3 - (ac)^3 = (2-ac)(4+2ac+a^2c^2)$$

г) $$m^3n^3 + 27 = (mn)^3 + 3^3 = (mn+3)(m^2n^2-3mn+9)$$

д) $$x^6y^3 - c^3 = (x^2y)^3 - c^3 = (x^2y-c)(x^4y^2+x^2yc+c^2)$$

е) $$a^3 - m^3n^3 = a^3 - (mn)^3 = (a-mn)(a^2+amn+m^2n^2)$$