${?}_{9.}{k}_e=8\mathrm{.}9876{10}^{9}N\frac{m^2}{C^2}$;${}_0=8\mathrm{.}8542{10}^{-12}\frac{C^2}{N}{m}^2.$

Q$1)$ In the figure shown, the particles have charges $q_1=-q_2=x,$ where $x$ is the last three digits in your university ID in $nC$ and $q_3=-q_4=2x$ and distance $a=5\mathrm{.}0cm.$ Find the net electric force vector $($magnitude and direction$)$ on particle $3.$

Q$2)$ In the figure to the right, three particles are fixed in place and have charges $q_1=x,$ where $x$ is the last three digits in your university ID in $C,q_2=-300C,q_3=700C.$ Distance $a=3\mathrm{.}00m.$ What is the net electric field vector $($magnitude and direction$)$ at point $P$ due to the particles?

Q$3)$ In the figure to the right, particle $1$ of charge $x,$ where $x$ is the last three digits in your university ID in $C$ and particle $2$ of charge $-200\mathrm{.}0C$ are held at separation $L=20\mathrm{.}0cm$ on an $x$ axis. If particle $3$ of unknown charge q $3$ is to be located such that the net electrostatic force on it from particles $1$ and $2$ is zero, what must be the $($a$)x$ and $($b$)y$ coordinates of particle $3?$