$x^4 + x^3 - 4x^2 + x + 1 = 0$两边同除 $x^2$，化为 $(x^2+\frac{1}{x^2}) + (x+...

crazyshou

\(\$x^4+x^3-4x^2+x+1=0\$两边同除\$x^2\$，化为\$(x^2+\frac{1}{x^2})+(x+\frac{1}{x})-4=0\$，令\$t=x+\frac{1}{x}\$\)