F(-2)=-(-2)^2+5*(-2)=-4-10=-14
Вот и всё!
2) m(m-2)(m+2)
(m(2m-20)+4m(m+2)-6(m²-4)/ m(m-2)(m+2)=(2m²-20m+4m²+8m-6m²+24)/m(m-2)(m+2)=(-12m+24)/ m(m-2)(m+2)=(-12(m-2)/m(m-2)(m+2)=
=(-12)/m(m+2)
4) (x+3)(х²-3x+9)
(х²-3x+9-х²+18)/(x+3)(х²-3x+9)=
=(-3x+27)/(x+3)(х²-3x+9)=(-3(x-9)/(x^3+27)
3) (m+n)(m²-mn+n²)
(2m²-n²-(m-n)(m+n)/(m+n)(m²-mn+ n²)=(2m²-n²-m²+n²)/(m^3+n^3)= m²/(m^3+n^3)
X³ - 3 * X² - 3 * X + 1 = (X³ + 1) - (3 * X² + 3 * X) = (X + 1) * (X² - X + 1) - 3 * X * (X + 1) =