数学帝啊……救命啊………!

2025-02-24 22:36:03
推荐回答(1个)
回答1:

(1)
f(x)=根号3sinxcosx+cos平方x+a
=(√3/2)sin(2x)+(1/2)(cos2x+1)+a
=sin(2x+π/6)+a+1/2
最小正周期为 2π/2=π
单调减区间:
2x+π/6∈[2kπ+π/2,2kπ+3π/2]
x∈[kπ+π/6,kπ+2π/3]
所以单调减区间为 [kπ+π/6,kπ+2π/3] k∈z

(2)
x∈[-π/6,π/3]
2x+π/6∈[-π/6,5π/6]
sin(2x+π/6)的范围为 [-1/2,1]
所以
y的值域为 [a,a+3/2]
所以a+a+3/2=3/2
得 a=0