a+b=-3,ab=1∴b=-3-aab=a(-3-a)=1∴a²+3a=-1∴a²+3a+1=0a³+8b=a³+3a²+a-3a²-9a-3+8a+8b+3=a(a²+3a+1)-3(a²+3a+1)+8(a+b)+3∵a²+3a+1=0a+b=-3∴ 原式=0-0-24+3=-21...