第1个回答 2015-03-26
f'(x)=2π/m*cos(πx/m)=0
代入x=1/2与x=1
π/(2m)< 2π
即m>1/4 , π/m<4π
1. π/(2m)<π/2<π/m
π/m<=3π/2
即有[2/3,2)
2. π/(2m)<3π/2<π/m
π/m<=5π/2
π/(2m)>= π/2
即有[2/5,2/3)
3. π/(2m)<5π/2<π/m
π/m<=7π/2
π/(2m)>=3π/2
即有[2/7,1/3]
4. π/(2m)<7π/2<π/m
π/m<4π
π/(2m)> 5π/2
即无解,
综合有[2/7,1/3],[2/5,2)本回答被网友采纳