Solving a problem in physics section 4 paragraph 98 ele

Solving a problem in physics section 4 paragraph 98 ele

98. Two point charges and 9Q -Q fixed distance l = 50 cm apart. The third charge Q1 can only move along a line passing through the charges. Determine the position of the charge Q1, in which it will be in equilibrium. At any sign of the charge Q1 equilibrium will be stable?

Additional information:

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)