1)
(a+x)³-a*(a+x)²-x²*(2a+x)-a²x=(a+x)²(a+x-a)+2ax²-a²x=
=(a²+2ax+x²)*x-2ax²-x³-a²x=a²x+2ax²+x³-2ax²-x³-a²x=0.
2)
(a-1)³+3*(a-1)²+3*(a-1)+1-a³=(a-1)²*(a-1+3)+3a-3+1-a³=
=(a²-2a+1)*(a+2)+3a+-2-a³=a³-2a²+a+2a²-4a+2+3a-2-a³=0.
1)
(a+x)³-a*(a+x)²-x²*(2a+x)-a²x=(a+x)²(a+x-a)+2ax²-a²x=
=(a²+2ax+x²)*x-2ax²-x³-a²x=a²x+2ax²+x³-2ax²-x³-a²x=0.
2)
(a-1)³+3*(a-1)²+3*(a-1)+1-a³=(a-1)²*(a-1+3)+3a-3+1-a³=
=(a²-2a+1)*(a+2)+3a+-2-a³=a³-2a²+a+2a²-4a+2+3a-2-a³=0.