g(b) = log(b)
h = 0.5 (slider from -0.5 to 0.5, step 1.0E-4)
f(b) = (b^(h) - 1) / h
text1: "$ " + (LaTeX[f]) + " $"
A: (5, f(5))
f_1(b) = (b^(h) - 1) / h
text1_1: "$ " + (LaTeX[f_1]) + " $"