x2+3x+1=0 两边同时除以 xx+3+1/x=0 x+1/x=-3 两边平方得 x2+2+1/x2=9 x2+1/x2=7 二边平方得:x4+2+1/x4=49x4+1/x4=47(x+1/x)(x2+1/x2)=x3+1/x+x+1/x3-3*7=x3+1/x3-3故x3+1/x3=-21+3=-18(x3+1/x3)(x4+1/x4)=x7+1/x+x+...