[x^(2/3)-x^(1/2)]/x=x^(-1/3)-x^(-1/2)=x^(-1/2)·(x^1/6-1), x趋于0时,x^(-1/2)趋于+∞,(x^1/6-1)趋于-1, 所以,x趋于0时,x^(-1/2)·(x^1/6-1)的极限是-∞.
