Объяснение:
1) (a+b)³+ (a-b)³=a³+3a²b+3ab²+b³-(a³-3a²b+3ab²-b³)=
=a³+3a²b+3ab²+b³-a³+3a²b-3ab²+b³=
=2b³+6a²b
2) 3 (2 - a)²+4 (a - 5)²= 3(4-4a+a²)+4(a²-10a+25)=
=7a²-52a+112
