Solve the equation by secant method

Question

Sequences Which Converge to Square Roots and Cube Roots

Explain the steps on how to solve the problem below:

Use the Secant method to show that sequence below converges to √Q, where Q > 0, given "good" starting values x₀ and x_{_1}:

x_n+1 = (x_nx_n-1 + Q) / (x_n + x_n-1).

Come up with a similar recursion for calculating Q^1/3 using the secant method.