求函数y=sin(π⼀3+4x)的周期 单调区间 最值

2025-03-10 16:25:49
推荐回答(2个)
回答1:

解:
(1)y=sin(π/3+4x)
周期为T=2π/w=2π/4=π/2
单调区间:
2kπ-π/2≤π/3+4x≤2kπ+π/2 (k∈Z)得
kπ/2-5π/24≤x≤kπ/2+π/24
即单调递增区间为[kπ/2-5π/24,kπ/2+π/24] (k∈Z)

2kπ+π/2≤π/3+4x≤2kπ+3π/2 (k∈Z)得
kπ/2+π/24≤x≤kπ/2+7π/24
即单调递减区间为[kπ/2+π/24,kπ/2+7π/24] (k∈Z)

最大值为1
最小值为-1

对称性:
π/3+4x=kπ+π/2 (k∈Z)得
x=kπ/4+π/24
即对称轴为
x=kπ/4+π/24 (k∈Z)

π/3+4x=kπ (k∈Z)得
x=kπ/4-π/12
即对称中心为(kπ/4-π/12,0)(k∈Z)

(2)y=sin(π/3-4x)=-sin(4x-π/3)
周期为T=2π/w=2π/4=π/2
单调区间:
2kπ-π/2≤4x-π/3≤2kπ+π/2 (k∈Z)得
kπ/2-π/24≤x≤kπ/2+5π/24
即单调递减区间为[kπ/2-π/24,kπ/2+5π/24] (k∈Z)

2kπ+π/2≤4x-π/3≤2kπ+3π/2 (k∈Z)得
kπ/2+5π/24≤x≤kπ/2+11π/24
即单调递增区间为[kπ/2+5π/24,kπ/2+11π/24] (k∈Z)

最大值为1
最小值为-1

对称性:
4x-π/3=kπ+π/2 (k∈Z)得
x=kπ/4+5π/24
即对称轴为
kπ/4+5π/24(k∈Z)

4x-π/3=kπ (k∈Z)得
x=kπ/4+π/12
即对称中心为(kπ/4+π/12,0)(k∈Z)

回答2:

函数y=sin(π/3+4x)的周期为2π/4=0.5π;
单调区间-π/2+2nπ≤π/3+4x≤π/2+2nπ,即-5π/24+nπ/2≤x≤π/24+nπ/2内递增,同理,π/24+nπ/2≤x≤7π/24+nπ/2内递减;
最大为1,最小为-1,非奇非偶(难道要说对称轴,那就是x为增减区间改变的点)

函数y=sin(π/3-4x)单调区间-π/2+2nπ≤π/3-4x≤π/2+2nπ,即π/24-nπ/2≤x≤5π/24-nπ/2内递减,同理,π/24-nπ/2≤x≤7π/24-nπ/2内递增;
同样非奇非偶