Solving Newton's Method for xn with y as a Constant

[DeadxBunny]

Homework Statement

Identify the formula

xn+1 = -2xn + 3yxn^(2/3)

as the Newton's method for a certain function. Here y is a fixed constant. What is the limit of xn?

Homework Equations

Newton's method?:

xn+1 = xn - f(xn)/f'(xn)

The Attempt at a Solution

I don't know how to begin.

Thanks in advance!

 

[christianjb]

1st step- Newton's method gives

x_n-x_{n-1}=f(x_n)/f'(x_n)

So rearrange your equation to get f(x_n)/f'(x_n). Then think.