x^2-3x+1=0 两边除xx-3+1/x=0x+1/x=3 平方x^2+2+1/x^2=9x^2+1/x^2=7 平方x^4+2+1/x^4=49x^4+1/x^4=47(x+1/x)(x^2+1/x^2)=x^3+1/x+x+1/x^3=3*7=21x^3+1/x^3=21-3=18(x^4+1/x^4)(x+1/x)=x^5+x^3+1/x^3+1/x^5=47*3=141x...