Срочно нужно сделать!!!
Ф(x) = kQ/x
Ф1 = Ф(x1) = kQ/x1
Ф2 = Ф(x2) = kQ/x2
Ф3 = Ф(x3) = kQ/x3
Ф2 - Ф3 = Ф1 - Ф2
kQ/x2 - kQ/x3 = kQ/x1 - kQ/x2
1/x2 - 1/x3 = 1/x1 - 1/x2
1/x3 = 2/x2 - 1/x1
1/x3 = 2/2 - 1/1 = 1-1 = 0
1/x3 = 0
x3 = беск.