a) 3ax²+4ax³+6a²x+8a²x² =
= ax(3x+4x²+6a+8ax) =
= ax[x(4x+3)+2a(4x+3)] =
= ax(x+2a)(4x+3)
b) 12a²b³+4a²b+9ab²+3a =
= a(12ab³+4ab+9b²+3) =
= a[(4ab(1+3b²) + 3(1+3b²)] =
= a(1+3b²)(4ab+3)
c) 2xy+3x²y-4x²y²-6x³y² =
= xy(2+3x-4xy-6x²y) =
= xy[(3x+2)-2xy(3x+2)] =
= xy(1-2xy)(3x+2)
d) 5x²+2a²x-10ax-4a³ =
= x(5x+2a²) - 2a(5x+2a²) =
= (x-2a)(5x+2a²)
