Four charges +0,25 nC, -3,00nC,-3,50 nC and +4,25nC are placed at the corners of square with sides of length 30,00 mum, place the -3,00nC charge on the negative x-axis, +2,25 cC charge on the positive x-axis the +4,25 nC charge and -3,50 nC charge directly above the =4,25 nC charge and the potential at the origin halfway between the positive and negative charge on the axis.