Consider the given data as below.
The charge,
The distance between two point charges, r = 0..5 m
The Coulomb’s constant, localid="1665130019862"
In example 21.4, the net force on Q is a repulsive force, but now Q has both repulsive and attractive forces. Therefore, the charge,
Because exerted repulsive forces in the negative direction of the y-axis with angle with the x-axis, the negative charge exerted an attractive force towards itself, so the y-axis direction will be;

Because the two forces acting on Q have the same magnitude, the net force in the new case will be;
Here, localid="1665130545351" . Therefore,
localid="1665130595651"
Substitute known values in the above expression, and you have
Hence, the net force is 0.35 N and its direction is in the negative y-direction.