已知函数f(x)=2cos2x+sin平方x-4cosx

f(x)=2cos2x+sin^x-4cosx=2(2cos^x-1)+(1-cos^x)-4cosx=3cos^x-4cosx-1f(π/3)=3cos^(π/3)-4cosπ/3-1=3x(1/2)^-4x1/2-1=(-9)/4;令t=cosx,t∈[-1,1].F(t)=3(t^2)-4t-1 F'(t)=6t-4 令F'(t)=0,t=2/3;t∈[-1,2/3],F(t)...