1)x^3-4x^2+20x-125 2)c^4+c^3y-cy^3-y^4 все по формуле a^3+b^3=(a+b)(a^2^-ab+b^2)

1)x^3-4x^2+20x-125=(x^3-125)+(20x-4x^2)=(x-5)(x^2+5x+25)-4x(x-5)=(x-5)(x^2+5x+25-4x)=(x-5)(x^2+x+25)
2)  c^4+c^3y-cy^3-y^4=c^3(c+y)-y^3(c+y)=(c+y)(c^3-y^3)=(c+y)(c-y)(c^2+cy+y^2)