Fixed Point Iteration for Solving Equations

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Huumah
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Homework Statement


Apply fixed point iteration to find the solution of each equation to eight correct decimal places

x3=2x+2



The Attempt at a Solution


I have tried to rewrite the equation for in every possible way to solve for one x and pluggin in my guess( have tried -2,-1,0,1,2,3,4)

and finding x1 and then x2 and plugging them all inn seperatly.

rIvNr0a.png


But my answer switches from positive values to negative values and never seems to be converging to the answer which is 1.76929235


I can understand the sample problem but I'm stuck on this problem.
 
on Phys.org
Huumah said:

Homework Statement


Apply fixed point iteration to find the solution of each equation to eight correct decimal places

x3=2x+2

The Attempt at a Solution


I have tried to rewrite the equation for in every possible way to solve for one x and pluggin in my guess( have tried -2,-1,0,1,2,3,4)

and finding x1 and then x2 and plugging them all inn seperatly.

rIvNr0a.png
The formula you show above is incorrect. It should be
$$ x_{n+1} = \frac{2(x_n + 1)}{x_n^2}$$
Huumah said:
But my answer switches from positive values to negative values and never seems to be converging to the answer which is 1.76929235I can understand the sample problem but I'm stuck on this problem.

If you start with x0 = 1, what are the next three numbers you get?
If you start with x0 = 2, what are the next three numbers you get?
 
Don't forget that there are conditions for a function to have a fixed point.

The expression I used is:

[itex] x_{n+1}=\sqrt { \frac { 2\left ( x_n + 1 \right )}{x_n} }[/itex]

Try with [itex]x_0 = 1[/itex] and [itex]x_0 = 2[/itex] and let me know.

J.