y=x²+1/xy'=2x-1/x²令y‘=0,解得x=0.5^(1/3)≈0.7937当02^(-1/3)时,y’>0x=2^(-1/3)≈0.7937时,极小值y=2^(-2/3)+2^(1/3)≈1.8899当x<0时,y'<0,即在x负半轴单调递减y=x²+1/x的递减区间是(-∞,0)∪(0,2^(-1/3)),递增区间是(2^(-1/3),+∞)描出几个关键点:x=-2,y=3.5x=-1,y=0x=0.5,y=2.25x=0.8,y=1.9x=1,y=2x=2,y=4.5用描点法连接是光滑曲线如图