y=kx+3/2
y^2-2y-x+3=0
k²x²+9/4+3kx-2(kx+3/2)-x+3=0
b²-4ac=(k-1)²-4k²(9/4)=0
8k²+2k-1=0
(2k+1)(4k-1)=0
k=-1/2 k=1/4