22-4

$${\vec{E} = \frac{\vec{F_0}}{q_0} = \frac{\vec{F_{01}}}{q_0} + \frac{\vec{F_{02}}}{q_0} + \dotsc + \frac{\vec{F_{0n}}}{q_0} = \vec{E_1} + \vec{E_2} + \dotsc + \vec{E_n}}$$