Bitcoin, Blockchain, Blockchain Technology, Cryptography, Cryptocurrency.
keep the rule valid in case of the vertical line we can say there is point at infinity that is part of the curve. The point at infinity is 0 in point addition. The Group law for the point at infinity: (x1, y1) = (x1, y1) + (inf, inf) (x1, y1) + (x1, -y1) = (inf, inf) (inf, inf) = 0 at point