Cf

x1 = 

x2 = 

x3 = 

\mathscr{C}_f

x_A = -1 (slider from -2 to 5, step 0.5)
f(x) = x^(3) - 5 * x^(2) + x + 1
A: (x_A, f(x_A))
T = Tangent(A, f)