x+1/x=3
两边平方
x^2+2+1/x^2=9
x^2+1/x^2=7
x^2/(x^4+x^2+1)
上下同除以x^2
=1/(x^2+1+1/x^2)
=1/(7+1)
=1/8
绝对保证,1星期9100分不是白拿的.