Question

Докажите тождество (2a+b)^3-(a-b)^2(8a+b)=27a^2b​

Answer 1

Ответ:

=a^3 - 6a^2b + 12ab^2 - 8b^3 - (a^2+2ab+b^2) (a-8b) =

=a^3 - 6 a^2b + 12ab^2 - 8b^3 - a^3 + 8a^2b - - 2a^2b+16ab^2-ab^2 + 8b^3 = 27 ab^2;

27ab^2 = 27ab^2