Question

Упростите выражение: (9 – у)(9 +у) – 3у(3у² - 1) + 9(у³ - 9).

Answer 1

(9-y)(9+y)-3y(3y^2-1)+9(y^3-9)=81-y^2-9y^3+3y+9y^3-81=3y-y^2=
=y(3-y)