1) $$8a - 12b = 4(2a - 3b)$$
2) $$3a - ab = a(3 - b)$$
3) $$6ax + 6ay = 6a(x + y)$$
4) $$4a^2 + 8ac = 4a(a + 2c)$$
6) $$12x^2y - 3xy = 3xy(4x - 1)$$
7) $$21a^2b + 28ab^2 = 7ab(3a + 4b)$$
8) $$-3x^6 + 12x^{12} = 3x^6(-1 + 4x^6)$$
9) $$4a^2 - 8a^3 + 12a^4 = 4a^2(1 - 2a + 3a^2)$$
10) $$6m^3n^2 + 9m^2n - 18mn^2 = 3mn(2m^2n + 3m - 6n)$$