Solving Newton's Method for f(x) = 0: Step-by-Step

In summary, the conversation discussed solving the equation f(x)=0 and using Newton's Method to find the second approximation of the solution. The first step was to manipulate the equation (1/x)^x - x = 0 to xln(1/x) = lnxx, and then use the fact that 1 to any power is 1 to simplify the equation further. This led to finding the solution for part A and proving that there is only one solution for part B. Finally, Newton's Method was used with an initial approximation of x1 = 1/2 to find the second approximation x2 of the solution in part C.
  • #1
EL ALEM
26
0

Homework Statement


Nother Q for today:
Let f(x)= (1/x)^x - x
(a)show that f(x)=0 has a solution
(b)show that there is only one solution to f(x)=0
(c)use Newton's Method to find the second approximation x2 of the solution to f(x) =
0 using the initial approximation x1 = 1/2


Homework Equations





The Attempt at a Solution


I know how to do part C just need a little kick in the right direction for the first part.

(1/x)^x - x = 0
(1/x)^x = x
xln(1/x) = lnx
 
Last edited:
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  • #2
EL ALEM said:
[tex]x \log(1/x) = \log(x)[/tex]

Remember what [tex]\log(a/b)[/tex] equals to? Break the pieces out.
 
  • #3
How about the simple fact that 1 to any power is 1?
 
  • #4
I already got it, it was late and I wasn't thinking straight, thanks for the replies though.
 

1. What is Newton's Method and why is it important in solving equations?

Newton's Method is an iterative method for approximating the roots of a function. It is important because it allows us to find solutions to equations that cannot be solved algebraically.

2. How does Newton's Method work?

Newton's Method works by starting with an initial guess for the root of the function and then using the derivative of the function to iteratively refine the guess until the desired level of accuracy is achieved.

3. What is the formula for Newton's Method?

The formula for Newton's Method is:
xn+1 = xn - f(xn) / f'(xn)
where xn is the current guess for the root, xn+1 is the next guess, f(x) is the function, and f'(x) is the derivative of the function.

4. How do you know when to stop iterating in Newton's Method?

You can stop iterating in Newton's Method when the difference between two consecutive guesses is less than a specified tolerance level, or when the function value at the current guess is close to zero.

5. Can Newton's Method be used for all types of equations?

No, Newton's Method is primarily used for finding the roots of a continuous function. It may not work for discontinuous functions or functions with multiple roots. In addition, it is not recommended for use with complex numbers.

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