a: \(\left(a-2b-3c\right)^2\)
\(=a^2+4b^2+9c^2-4ab-6ac+12bc\)
b: \(\left(2a-b+3c\right)^2\)
\(=4a^2+b^2+9c^2-4ab-6bc+12ac\)
d: \(8a^3+b^6=\left(2a\right)^3+\left(b^2\right)^3\)
\(=\left(2a+b^2\right)\left(4a^2-2ab^2+b^4\right)\)
e: \(8a^3-b^6=\left(2a-b^2\right)\left(4a^2+2ab^2+b^4\right)\)
f: \(a^6-b^6=\left(a-b\right)\left(a+b\right)\left(a^2-ab+b^2\right)\left(a^2+ab+b^2\right)\)