问题
选择题
定义一种运算a⊕b=
|
答案
由于cos2x+sinx=-sin2x+sinx+1=-(sinx-
)2+1 2
≤5 4 5 4
∴f(x)=(cos2x+sinx)⊗
=cos2x+sinx,5 4
f(x-
)=cos2(x-π 2
)+sin(x-π 2
)=sin2x-cosx=-(cos2x+cosx+π 2
)+1+1 4
=-(cosx+1 4
)2+1 2
≤5 4 5 4
故选A