
第二题的答案
2个回答
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2.
f'(x)=1-2sinx
令f'(x)≤0
1-2sinx≤0
sinx≥½
x∈[0,π/2],π/6≤x≤π/2
f(x)的单调递增区间为[0,π/6],f(x)的单调递减区间为[π/6,π/2]
f(0)=2cos0+0=2+0=2
f(π/2)=2cos(π/2)+ π/2=π/2<2
函数f(x)在[0,π/2]上的最小值为π/2
f'(x)=1-2sinx
令f'(x)≤0
1-2sinx≤0
sinx≥½
x∈[0,π/2],π/6≤x≤π/2
f(x)的单调递增区间为[0,π/6],f(x)的单调递减区间为[π/6,π/2]
f(0)=2cos0+0=2+0=2
f(π/2)=2cos(π/2)+ π/2=π/2<2
函数f(x)在[0,π/2]上的最小值为π/2
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