1/x=3,x=1/3,x2+(1/x2)=(1/3)2+(1/(1/32))=1/9+9=82/9
82/9解析：//1/x=3x²+1/x²=(1/3)²+(1/x)²=1/9+3²=1/9+9=82/9
x +1/x = 3x^2 +1/x^2=(x+1/x)^2 -2=9-2=7
解：1/x=3x=1/3x²+1/x²=(1/3)²+1/(1/3)²=1/9+1/1/9=82/9
