(a-b)(a+b)(a-3b)=

(x+3)(2x-1)(3x+2)

(a-b)(a+b)(a-3b)=(a²-b²)(a-3b)==a²•a + a²•(-3b) - b²•a - b²•(-3b)==a³ - 3a²b - b²a + 3b³(х+3)(2х-1)(3х+2)==(х•2х + х•(-1) + 3•2х +3•(-1))(3х+2)==(2х²-х+6х-3)(3х+2)==(2х²+5х-3)(3х+2)==2х²•3х + 2х²•2 +5х•3х + 5х•2 - 3•3х - 3•2==6х³+4х²+15х²+10х-9х-6==6х³+19х²+х-6