Electrostatics

$-\left(\frac{5 Q}{8 \pi \epsilon_0 R^2}\right)(\hat{i}-3 \hat{j})$

$\frac{Q}{4 \pi \in_{\mathrm{o}} R^2}(\sqrt{3} \hat{i}-\hat{j})$

$-\frac{\mathrm{Q}}{4 \pi \in_{\mathrm{o}} R^2}(\sqrt{3} \hat{i}-\hat{j})$

$-\frac{5 Q}{8 \pi \epsilon_{\mathrm{o}} R^2}(\hat{i}+\sqrt{3} \hat{j})$