2a²-8b²
=2(a^2-4b^2)
=2(a+2b)(a-2b)
2m³-8m
=2m(m^2-4)
=2m(m+2)(m-2)
3a²-12ab+12b²
=3(a^2-4ab+4b^2)
=2(a-2b)^2