f(x) = ((-1 / 4 * (x - 3)) * (x + 1))
C = (-5.301088270858524, -0.5306358381502907)
D = (4.866082224909313, -0.4760115606936463)
h: 2
A: (h, f(h))
g = Tangent(A, f)
B: (-2, f(-2))
E = Intersect(g, xAxis)
f'(x) = f'(x)
a = 2 (slider from -6 to 5, step 0.1)
p(x) = (f'(a) * (x - a)) + f(a)
q = Expand(p)