Neutral Point between point charges

Electric fields are vector quantities, having both magnitude and direction. So what directions do you assign to the two magnitudes that you've calculated? What's their sum?

 

See if you can find a picture of the electric field surrounding a positive charge, and for a negative charge (your text or the web should have this). What direction are the arrows representing the fields directed in each case?

 

That's just the problem statement. You're expected to know the directions to assign to the fields produced by positive and negative charges. See if you can find another image showing the fields surrounding charges. I found several in a few seconds by googling "electric field".

 

Okay! So now you can assign a direction to the sum of the fields that you calculated earlier, right?

 

At point P sketch in the arrows representing the field direction from the two positive charges (along the line that all the charges lie). Suppose you choose the direction to the right to be the +x-axis direction. Now, those arrows (vectors) have the magnitudes that you calculated previously. What's the resultant of adding them?

 

Yes, that's the idea. You set up coordinate axes and determine both the magnitude and directions of the fields due to each charge before you start adding or subtracting them as the situation warrants. You will find that the same concept applies even if the charges are not along a straight line, in which case you'll deal will all the components of the vectors (time to review your trigonometry!).