View attachment 133907giải chi tiết gíup ạ.........
[tex]y=\sqrt{1+\frac{1}{2}cos^2x}+\sqrt{\frac{5}{4}+\frac{1}{2}sin^2x}[/tex]
Dùng Bunhia [tex]\Rightarrow y^2\leq (1^2+1^2)\left ( 1+\frac{1}{2}cos^2x+\frac{5}{4} +\frac{1}{2}sin^2x\right )\Rightarrow y^2\leq \frac{11}{2}\Rightarrow y\in \left [ \frac{-\sqrt{22}}{2};\frac{\sqrt{22}}{2} \right ][/tex]