令m=x+2/xm²=x²+4/x²+4原式变为m²-4=3mm²-3m-4=0(m-4)(m+1)=0x+2/x-4=0或x+2/x+1=0x²-4x+2=0或x²+x+2=0(无实数解)x=(4±2√2)/2x=2±√2验根...