如题所述
f ‘【x】=0有三处:x1<x2<x3
1/3 (6 - Sqrt[6]), 2, 1/3 (6 + Sqrt[6])
f ''[x1]<0 ,f''[2]<0, f''[x3]>0
极大值 无极值 极小值
7 - 2 Sqrt[6] 7 + 2 Sqrt[6]
x < 1/3 (6 - Sqrt[6]) || x > 1/3 (6 + Sqrt[6])单调增;
1/3 (6 - Sqrt[6]) <= x < 2 || 2 < x <= 1/3 (6 + Sqrt[6])单调减;