令a=x/3-4/xa²=x²/9-8/3+16/x²所以x²/3+48/x²=3(a²+8/3)=10a3a²-10a+8=0(a-2)(3a-4)=0x/3-4/x=2x²-6x+12=0无解x/3-4/x=4/3x²-4x-4=0x=2-2√2,x=2+2√2