Modifier la valeur de m 

 \vec{ u } 

m = -3.4 (slider from -5 to 5, step 0.1)
d_m: (2.0 * m - 1.0) * x - m * y + 3.0 * m + 1.0 = 0.0
B = (2, -1)
C = Intersect(xAxis, yAxis)
u = Vector(C, B)