(8-a³)/(16-a²) . (a+4)/(a²+2a+4)=(a³-8)/(a²-16) . (a+4)/(a²+2a+4)=
=(a-2)(a²+2a+4)/(a+4)(a-4) . (a+4)/(a²+2a+4)=
=(a-2)/(a-4) , a≠-4,a≠4
(9x²+24xy+16y²)/(9x²-16y²)=(3x+4y)²/(3x+4y)(3x-4y)=(3x+4y)/(3x-4y)
x≠-4y/3, x≠4y/3
(Formula: A²-B²=(A+B)(A-B), A³-B³=(A-B)(A²+AB+B²))