分析:降次
x^2=5x-1
所以(x^4+1)/x^2
=[(5x-1)^2+1]/(5x-1)
=(25x^2-10x+2)/(5x-1)
=[25(5x-1)-10x+2]/(5x-1)
=(115x-23)/(5x-1)
=23