- 3cos4x+32sin2x+mcosx−52y=3 \cos ^{4} x+\frac{3}{2} \sin ^{2} x+m \cos x-\frac{5}{2} đồng biến trên khoảng (π3;2π3]\left(\frac{\pi}{3} ; \frac{2 \pi}{3}\right]
- m≤−1√3m \leq-\frac{1}{\sqrt{3}}
- m≥−1√3m \geq-\frac{1}{\sqrt{3}}
- m<−1√3m<-\frac{1}{\sqrt{3}}
- m>−1√3m>-\frac{1}{\sqrt{3}}