Electric field on the axis of a system (-q, + q) - Corrected exercises of electromagnetism

Electric field on the axis of a (- q + q).

we have two point electrical charges carried by a x'Ox axis: - q on A (-a) and +q on B (+a) with q positive.

1. Express the electric field created by M (x) by the distribution in space, M belonging to the x'Ox axis.