解由题知y=2x+x^(2/3)求导y'=2+2/3x^(-1/3)即y'=2+2/3/x^(1/3)令y'=0即2+2/3/x^(1/3)=0即2x^(1/3)=-2/3即x^(1/3)=-1/3即x=-1/27即函数的极值点为-1/27把x=-1/27代入Y=2X+∛(x^2 )得y=2*（-1/27)+1/9=1/27即函数...