f(x) = x^(4.0) - 5.0 * x^(2.0) + 2.0
A: (-1.0, f(-1.0))
h = 1.8 (slider from -1.2 to 3.2, step 0.1)
B: (-1.0 + h, f(-1.0 + h))
a = Line(A, B)