Two charges q1 = 5 µc, q2 = -26 µc, are l = 19 cm apart. a third charge is to be placed on the line between the two charges. how far from q1 should the third charge be placed so that the net electric force on the third charge is minimized?

The electric between two objects is proportional to the product of the charge of the two objects  and inversely proportional to square of the distance betweeen them. In this case, the length between the original charges is 19 cm. We setup the equation k q1 q3/ (x)^2 = k q2 q3/ (19-x)^2 where x is the distance between q1 and q3. q3 is cancelled out. q2 is taken with an absolute value. x is equal to 5.79 cm.