a²-3a+1=0两边同除以aa-3+1/a=0a+1/a=3 (1)两边平方 a²+2+1/a²=9a²+1/a²=7 (2)代数式a三次方/（a六次方+1）=1/(a³+1/a³)=1/[(a+1/a)(a²-1+1/a²)]=1/[3*(7-1)]=1/18...