Newton-Raphson & Bisection Methods to Find x2- 2 Root

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Homework Statement



Using the Newton raphson method with x0=6, find the root of x2- 2 to 3dp.

Then estimate the number of iterations the bisection method that would be required to achieve the same accuracy.

Homework Equations





The Attempt at a Solution



I have done the first part with the Newton raphson method and have found that at x5 and x6 the answer of the root of the function is 1.414

However I am not sure how to estimate the number of iterations the bisection method will use, my guess is you use the following formula:

make the interval [1,2] (b=2, a=1) and k= accuracy
then

n must be greater than or equal to: log(b-a)+klog10/ log2
 
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Assuming k is the number of decimal digits in the precision (i.e. k = 6 for a precision of 10-6) and assuming you just forgot to type a parenthesis around the two log terms before diving with log 2, I get same result. If that is any help at this time :smile:
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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