A point charge q1 = 4.10 nc is placed at the origin, and a second point charge q2 = -3.10 nc is placed on the x-axis at x=+ 20.0 cm . a third point charge q3 = 1.95 nc is to be placed on the x-axis between q1 and q2. (take as zero the potential energy of the three charges when they are infinitely far apart.)