-2х - 12 = 6
-2х = 6+12
-2х = 18
Х = 18 : (-2)
Х = - 9
1/n(n+1) -1/(n+1)(n+2)=(n+2-n)/n(n+1)(n+2)=2/n(n+1)(n+2)
Ответ:
a²-ab²-ab-4b³-a³-3a²b
Объяснение:
(a-b)(a+2b²)-(a+b)³-b³=a²+2ab²-ab²-2b³-(a+b)³-b³=a²+2ab²-ab²-2b³-(a³+3a²b+3ab²+b³)-b³=a²+2ab²-ab-2b³-a³-3a²b-3ab²-b³-b³=a²-ab²-ab-4b³-a³-3a²b.