y=3sin(2x+π/4)
设:A=2x+π/4
则有增区间:A[2kπ-π/2,2kπ+π/2]
即:2x+π/4 [ 2kπ-π/2,2kπ+π/2]
2x [2kπ-3π/4,2kπ+π/4]
x [kπ-3π/8,kπ+π/8]
同理可推得:
减区间为 [kπ+π/8,kπ+5π/8]
y=1+sinx
y=-cosx
是正弦余弦函数
y=3sin(2x+π/4)
设:A=2x+π/4
则有增区间:A[2kπ-π/2,2kπ+π/2]
即:2x+π/4 [ 2kπ-π/2,2kπ+π/2]
2x [2kπ-3π/4,2kπ+π/4]
x [kπ-3π/8,kπ+π/8]
同理可推得:
减区间为 [kπ+π/8,kπ+5π/8]
y=1+sinx
y=-cosx
是正弦余弦函数