F'x=2(x-y)+2(x/3+3/y)/3=0, 得：-y+10x/9+1/y=0, 得：x=0.9(y-1/y)F'y=2(y-x)-2(x/3+3/y)*3/y^2=0, 得：y-x-(x+9/y)/y^2=0, 代入x,化简得：y^4=81, 因此y=3或-3y=3时,x=0.9(3-1/3)=2.4y=-3时,x=-2.4f(2.4,3)=0.6^...