i was absent for a few days and i am completely confused.  any help or guidance would be amazing.



for #1 first i found the diagonal distance equals
then i used the formula F=KC x q1 x q2/ to find the electric force between the 8nC charge and the two others:
8.99E9(8E-6 x 7E-6)/ 98 = 5.14E-3
and 8.99E9(8E-6 x 2E-6)/ 98 = 1.47E-3

after that i had no clue, except i know #4 is 0