(Solved): Charge q1=+q is located at position (0,d). Charge q2=4q1 is located at position (d,0). ...

Charge $q_1=+q$ is located at position $(0,d)$. Charge $q_2=?4q_1$ is located at position $(d,0)$. Charge $q_3=7q_1$ is located at position $(2d,2d)$. Determine the net electric field ${\vec{E}}_{\text{net }}$ at the origin in terms of the given quantities and physical constants, including the permittivity of free space ${?}_0$. Express the electric field using $\mathbf{ij}$ unit vector notation. Enter precise fractions and roots rather than entering their approximate numerical values.