f'(x)=2x-1/x²=(2x³-1)/x²,
增：[(1/2)^(1/3),+∞),减(-∞,(1/2)^(1/3)]
极小:(1/2)^(2/3)+2^(1/3)
f''(x)=2+2/x³,令f''(x)=0,得 x=-1
凹：(-1,+∞),凸：(-∞,-1)
拐点：x=-1,(-1,1)