Question

(1 - 4a³) . (1 + 4a³)

Answer 1

(1-4a³).(1+4a³)=1-16a^6)

Answer 2

Produto notável ... 

$(1-4a^{3}).(1+4a^{3})\\\\1.1+1.4a^{3}-4a^{3}.1-4a^{3}.4a^{3}\\\\1+4a^{3}-4a^{3}-16a^{6}\ =\ \boxed{\boxed{\ 1\ -\ 16a^{6}\ }}\ \ \ \ \ \ \ \ \ \ ok$