p1p=(x+1,6)
p1p2=(3,9)
(3,9)=k(x+1,6)
x=1
p1p=(2,6)
pp2=(1,3)
p1p=(2,6)=2pp2
r1=2
p2p1=(-3,-9)
p1p=(2,6)
p2p1=(-3,-9)=-3/2(2,6)=-3/2p1p
r2=-3/2