y cosx函数的单调区间(函数ycosx)
y cosx函数的单调区间(函数ycosx)自变量x的取值范围计算如下:2.当cos(x 3)<0,此时y=-cos(x 3) 2kπ-π/2≤x 3π≤2kπ π/2,k∈Z。 2kπ-π/2-3π≤1x≤2kπ π/2-3π, (4k-7)π/2≤x≤(4k-5)π/2
函数y=|cos(x 3π)|的单调增和减区间根据三角函数性质,结合绝对值有关性质,介绍绝对值三角函数y=|cos(x 3π)|的单调增和减区间。
去绝对值步骤1.当cos(x 3π)≥0,此时y=cos(x 3π)
自变量x的取值范围计算如下:
2kπ-π/2≤x 3π≤2kπ π/2,k∈Z。
2kπ-π/2-3π≤1x≤2kπ π/2-3π,
(4k-7)π/2≤x≤(4k-5)π/2
2.当cos(x 3)<0,此时y=-cos(x 3)
自变量x的取值范围计算如下:
2kπ π/2<x 3π<2kπ 3π/2,k∈Z。
2kπ π/2-3π<x<2kπ 3π/2-3π,
(4k-5)π/2<x<(4k-3)π/2
1. 当y=cos(x 3π)时,
在(4k-7)π/2≤x≤(4k-5)π/2区间上,
取x 3π=2kπ 0,则x=(2k-3)π,
增区间为:[(4k-7)π/2 (2k-3)π];
减区间为:[(2k-3)π (4k-5)π/2].
2.当y=-cos(x-3π)时,
在(4k-5)π/2<x<(4k-3)π/2区间上,
取x 3π=2kπ π 则x=(2k-2)π 此时有:
增区间为:[(4k-5)π/2 (2k-2)π);
减区间为:((2k-2)π (4k-3)π/2].
综上所述,此时绝对值函数y=|cos(x 3π)|的单调区间为:
单调增区间为:
[(4k-7)π/2 (2k-3)π] [(4k-5)π/2 (2k-2)π);
单调减区间为:
[(2k-3)π (4k-5)π/2] ((2k-2)π (4k-3)π/2]。