Total Force on Point Charge from 2 Point Charges/Also presented as

Total Force on Point Charge from 2 Point Charges: Also presented as
This can also be presented as:

where:
 * $\mathbf F_{21} + \mathbf F_{31}$ denotes the vector sum of $\mathbf F_{21}$ and $\mathbf F_{31}$
 * $\mathbf r_{ij}$ denotes the displacement from $q_i$ to $q_j$
 * $r_{ij}$ denotes the distance between $p_i$ and $p_j$
 * $\varepsilon_0$ denotes the vacuum permittivity.