Question

Помогите номер 2.8(В)

Answer 1

(a+b)³-(a-b)³=a³+3a²b+3ab²+b³-(a³-3a²b+3ab²-b³)=
=a³+3a²b+3ab²+b³-a³+3a²b-3ab²+b³=6a²b-6ab².

Тогда
(((a+b)³-(a-b)³)/2b(3a²+b²))  +1 = ((6a²b-6ab²)+2b(3a²+b²))/2b(3a²+b²)=

= (6a²b-6ab²+6a²b+2b³)/(2b(3a²+2b²))=(12a²b-6ab²+2b³)/(2b(3a²+b²))=

=2b(6a²-3ab+b²)/2b(3a²+2b²)= (6a²-3ab+b²)/(3a²+2b²).