Question $4$: $(2$ points$)$

The figure shows a line segment extending along the $y-$axis from $y=-0\mathrm{.}40m$ to $y=+0\mathrm{.}40m$ and carrying a total charge $+5\mathrm{.}0C.$ Answer the following two questions:

A$.$ Given that the electric field strength at a point on the $x$ axis is $E=\frac{k_{e}Q}{x\sqrt[\phantom{2}]{x^2+a^2}},$ find the electric field at a point P on the $x-$axis at $x=2\mathrm{.}0m.$

B$.$ Show that the above formula reduces to that of a point charge when the point $P$ becomes very far from the line segment.