1. The problem statement, all variables and given/known data Particles 1 and 2 are fixed in place on an x-axis at a separation of L=8cm. Their charges are q1=e q2=-27e. Particle 3 with charge q3=4e is to be placed on the line between particles 1 and 2, so that they produce a net electrostatic force F3net on it. a) at what coordinate should particle 3 be placed to minimize the magnitude of that force. 2. Relevant equations F=(1/4piε)qq/r^2 3. The attempt at a solution Both forces are acting rightward. So Fnet=(1/4piε)(q1*q3)/x^2+(1/4piε)(q2*q3)/(8-x)^2 This simplifies down to Fnet=e^2/piε(1/x^2+27/(8-x)^2) Now take the derivative to minimize function d(Fnet)/dx=(54e^2x^3-2e^2(8-x)^3)/piε(8-x)^3x^3 Set it to zero and my polynomial in the numerator is 8e^2(7x^3-6x^2+48x+128) and there is no min value in between 0 and 8!!!!!!!!!!!! Please help.