Tính 2 sqrt8-2 sqrtfrac12-sqrt18

$2 \sqrt{8}-2 \sqrt{\frac{1}{2}}-\sqrt{18}=2 \sqrt{2^{2} \cdot 2}-\sqrt{2^{2} \cdot \frac{1}{2}}-\sqrt{3^{2} \cdot 2}$

$=4 \sqrt{2}-\sqrt{2}-3 \sqrt{2}=(4-1-3) \cdot \sqrt{2}=0 \cdot \sqrt{2}=0$