А)6c^3-6=6(c-1)(c^2+c+1)
Б) (x^2+1)^2-4x^2=(x^2+1-2x)(x^2+1+2x)=(x^2-2x+1)(x^2+2x+1)=(x-1)^2(x+1)^2
В)a^2-2ay+y^2+a-y=(a-y)^2+a-y=(a-y)(a-y+1)
