<p>hey guys,</p>
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<p>could you explain it?</p>
<p>Hi
By convention the direction of an electric field is in the direction AWAY from a positive charge (and TO a negative charge).</p>
<p>The electric field in P caused by +Q alone is E to the right (since +Q is positive).</p>
<p>when you add the -Q charge, you add an electric field equal in magnitude (E=KQ/r^2 - I guess you have to assume that P is exactly in the middle) in the direction TO it (the right side).</p>
<p>Summing it all up you get a 2E electric field to the right side
and thats the answer.</p>
<p>thanks man :)</p>