ocr: P+C-0+P-Ploral PEEIZ,) 21P-(JEE(p then (X)+(X-) O.(The point (X-Y is denoted by -P.andis called the negative ofP:ob- serve: that- -Pis indeed a point on the curve.) 3.L LetP= XXEEUEp) and Q=(K2.Y) EE(LA where P7-Q.1 Then P+Q (X3.%3). - where Xa = 12-X1-X2 Y=A&-X)-y, and V2-X ifPQ X2-X L= 3x,2+a1 P=Q 2y, Figure 4: The addition rule.