Question

-5/2(вектор AB+вектор BC-1/2вектораAC)

Answer 1

$\bar{AB}+\bar{BC}=\bar{AC}$

$\bar{AC}- (1/2)\cdot \bar{AC}=(1/2)\bar{AC}\\(-5/2)\cdot (1/2)\bar{AC}=(-5/4)\bar{AC}$