با توجه به تصویر $\begin{align}  & {{F}_{21}}=\frac{k\left| {{q}_{2}}{{q}_{1}} \right|}{{{r}^{2}}}=\frac{9\times {{10}^{9}}\times 6\times 2\times {{10}^{-12}}}{4}=2/7\times {{10}^{-2}}N\Rightarrow {{\overrightarrow{F}}_{21}}=(-2/7\times {{10}^{-2}}N)\overrightarrow{i} \\  & {{F}_{31}}=\frac{k\left| {{q}_{3}}{{q}_{1}} \right|}{{{r}^{2}}}=\frac{9\times {{10}^{9}}\times 2\times 2\times {{10}^{-12}}}{4}=9\times {{10}^{-3}}N=0/9\times {{10}^{-2}}\Rightarrow {{\overrightarrow{F}}_{31}}=(0/9\times {{10}^{-2}}N)\overrightarrow{j} \\  & {{\overrightarrow{F}}_{Kol}}=(-2/7\times {{10}^{-2}}N)\overrightarrow{i}+(0/9\times {{10}^{-2}}N)\overrightarrow{j} \\ \end{align}$