求f(x)=xsinx+cosx-π⼀2,x∈[0,π]零点

2025-02-25 05:05:31
推荐回答(2个)
回答1:

解:
f'(x)=sinx+xcosx-sinx=xcosx
令f'(x)≥0,xcosx≥0
x∈[0,π],cosx≥0
0≤x≤π/2
f(x)在[0,π/2]上单调递增,在[π/2,π]上单调递减
当x=π/2时,f(x)取得最大值
f(π/2)=(π/2)sin(π/2)+cos(π/2)- π/2=π/2+0-π/2=0
x∈[0,π]且x≠π/2时,f(x)恒<0
f(x)在[0,π]上有唯一零点x=π/2

回答2:

π/2啊