X平方—3X+1=0x²+1=3x两边同除以x得：x+1/x=3两边平方得：x²+1/x²=9-2=7(x-1/x)²=7-2=5x-1/x=±√5x³-1/x³=(x-1/x)(x²+1+1/x²)=±√5*(7+1)=±8√5X三次方除以X的六次方-1...