[tex]F_K=\frac{k}{\varepsilon} \frac{q_1q_2}{r^2}[/tex]

Для данной задачи:

[tex]F=\frac{k}{\varepsilon} \frac{2q^2}{r^2}[/tex]

[tex]F\frac{\varepsilon}{k} r^2= 2q^2\\\frac{F\varepsilon r^2}{2k} = q^2\\q=\sqrt{\frac{F\varepsilon r^2}{2k}}[/tex]

[tex]q_1=q=\sqrt{\frac{F\varepsilon r^2}{2k\\} } \\q_2=2q=\sqrt{\frac{2F\varepsilon r^2}{k} }[/tex]

[tex]q_1=\sqrt{\frac{10^{-6}*720*5*(25*10^{-3})^2}{9*10^9} } =\frac{50\sqrt{10} }{10^{10}} =1,6*10^{-8}[/tex] Кл

[tex]q_2=2q_1=3,2*10^{-8}[/tex] Кл