a²-3a+1=0
同时除以a,得:
a-3+1/a=0
a+1/a=3
(a+1/a)²=9
a²+2+1/a²=9
a²+1/a²=7
a³+1/a³
=(a+1/a)(a²-a*1/a+1/a²)
=3*(7-1)
=18
a³/(a^6+1)
=1/(a³+1/a³)
=1/18
a²-3a+1=0
同时除以a,得:
a-3+1/a=0
a+1/a=3
(a+1/a)²=9
a²+2+1/a²=9
a²+1/a²=7
a³+1/a³
=(a+1/a)(a²-a*1/a+1/a²)
=3*(7-1)
=18
a³/(a^6+1)
=1/(a³+1/a³)
=1/18