A = (3.7800000000000002, 3.5)
B = (4.84, 2.02)
u = Vector(A, B)
a = -2.3 (slider from -5 to 5, step 0.1)
v = Vector(A, Translate[A, a * UnitVector[u]])
C = (0.8200000000000001, 2.4)
D = (2.7, 3)
w = Vector(C, D)
z = vtNrMult(C, w, a)

Tool: vtNrMult
Input: A, u, a
Output: v

v = Vector(A, Translate[A, a * UnitVector[u]])