(z-1)(z+4) = z²+4z-z-4 = z²+3z-4
(b+4)(c+5) = bc+5b+4c+20
(c-4)(d-3) = cd-3c-4d+12
(x+y)(x+1) = x²+x+xy+y
(a²+b)(a+b²) = a³+a²b²+ab+b³
(a²+2b)(2a+b²) = 2a³+a²b²+4ab+2b³
(2a-b)(4a²+2ab+b²) = 2³a³-b³ = 8a³-b³ разность кубов
(5x+3y)(25x²-15xy+9y²) = 5³x³+3³y³ = 125x³+27y³ сумма кубов