A:①②
B:②③
C:③④
D:②③④
下列运算正确的是( )
已知fx=3cosx+3π2+cosx-3π2+sinx+π+a(a∈R,a为常数).
(1)若f(x)为奇函数,求a的值;
(2)若x∈R,求f(x)的最小正周期;
(3)若x∈0,π2时,f(x)的最大值为4,求a的值.
若直线y=2x﹣b在x轴上的截距为1,则b=( )
Don't eat ____ (such/so) many hamburgers a day. It's bad for your health.