x²-5x-1=0 两边同时除以x得x-5-1/x=0x-1/x=5x²/(x的4次方+x²+1)=1/(x²+1+1/x²)=1/[(x²-2+1/x²)+3]=1/[(x-1/x)²+3]=1/(5²+3)=1/(25+3)=1/28请点击下面的【选为满意回答...