函数f(x)=cos1/4xcos(π/2-x/4)cos(π-x/2)在区间(0.+∞)内全部的极值点按从小到大排成数列an,求通项
问题描述：
函数f(x)=cos1/4xcos(π/2-x/4)cos(π-x/2)在区间(0.+∞)内全部的极值点按从小到大排成数列an,求通项
答
f(x)=cos(x/4)cos(π/2-x/4)cos(π-x/2)f'(x)=(1/2)cos(x/4)cos(π/2-x/4)sin(π-x/2)+ (1/4)cos(x/4)cos(π-x/2) sin(π/2-x/4)-(1/4)cos(π/2-x/4)cos(π-x/2)sin(x/4)= (1/2)cos(x/4)sin(x/4)sin(x/2)- (1/4)cos(...