$\Large \vec{u}$

$\Large\vec{a}$

$\Large r\vec{u}$

$\Large  \vec{x} =\vec{a} + r  \vec{u}$

A = Intersect(xAxis, yAxis)
B = (3, 1)
C = (-1, 3)
u = Vector(B)
v = Vector(C)
f = Line(C, u)
r = 2.5 (slider from -5 to 5, step 0.5)
w: (r * u)
D = Point(C, w)
a = Vector(C, D)
E = Point(A, w)
v1, a_1, e, d, c = Polygon(A, E, D, C)
b = Vector(D)
Text1: "\vec{x}=\vec{a} + r \vec{u}\\ \\ \\
\vec{x}=" + (LaTeX[v]) + "+r" + (LaTeX[u]) + "\\ \\ \\" + (LaTeX[b]) + "=" + (LaTeX[v]) + "+" + (LaTeX[r]) + "" + (LaTeX[u]) + ""