Attraction of -Q to +Q in x and y directions

1. The problem statement, all variables and given/known data

Find the magnitude and direction of the force on the charge -Q on the figure in the attached document.

2. Relevant equations

F = k(q)(Q)/r²r-hat


3. The attempt at a solution

So I have a force in the x direction and a force in the y direction.

F_x = k(Q1)(-Q)/(a) x-hat

F_y = (k)(Q2)(-Q)/(a) y-hat

F = F_x + F_y = -kQ²2/(a)² x-hat + -kQ₁²/a² y-hat

Is this right? Or can more be done to solve it?
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution