$\sqrt{1+2\sin \dfrac{x}{2} \cos \dfrac{x}{2} }+\sqrt{1-2\sin \dfrac{x}{2} \cos \dfrac{x}{2} }$
$=\sqrt{(\sin \dfrac{x}{2} +\cos \dfrac{x}{2})^2} +\sqrt{(\sin \dfrac{x}{2} -\cos \dfrac{x}{2})^2}$
$=\sin \dfrac{x}{2} +\cos \dfrac{x}{2} +\bigg | \sin \dfrac{x}{2} -\cos \dfrac{x}{2} \bigg |$
Tới đó tự xét trường hợp nhá