x^4+x^3+9x^2/4+x+1=0木有有理根.只能强配凑一下
x^4+x^3+9x^2/4+x+1
=(x^2 + x/2 )^2 +2x^2 +x +1
=x^2 + x/2 +2(x^2 +x/2) +1
=(x^2 +x/2 +1)^2