Math Problem Statement

Use Newton's Method to approximate the zero(s) of the function f(x) = x - 4√(x + 3) accurate to three decimal places.

Solution

We are asked to use Newton's Method to approximate the zero(s) of the function f(x)=x4x+3f(x) = x - 4\sqrt{x + 3} to three decimal places.

Steps for Newton's Method:

  1. Initial Guess: Choose a starting value x0x_0 close to where the root might be.
  2. Iteration Formula: Newton’s method uses the iterative formula: xn+1=xnf(xn)f(xn)x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)} where f(x)f'(x) is the derivative of f(x)f(x).

Step 1: Function and Derivative

The given function is f(x)=x4x+3f(x) = x - 4\sqrt{x + 3}.

Derivative f(x)f'(x):

f(x)=142x+3=12x+3.f'(x) = 1 - \frac{4}{2\sqrt{x+3}} = 1 - \frac{2}{\sqrt{x+3}}.

Step 2: Iteration

Using the iterative formula for Newton's method: xn+1=xnxn4xn+312xn+3.x_{n+1} = x_n - \frac{x_n - 4\sqrt{x_n + 3}}{1 - \frac{2}{\sqrt{x_n + 3}}}.

Step 3: Choose Initial Guess

Let's try an initial guess of x0=1x_0 = 1, and apply the iterative process until the value stabilizes to three decimal places.

Let me compute the iterations.It seems that the derivative function f(x)f'(x) caused a division by zero error at some point, likely because x+3\sqrt{x+3} became too small. This might happen if the guess is too far from the root or if the value of x+3x+3 approaches zero.

To avoid this, let's try a larger initial guess for x0x_0, since the term x+3\sqrt{x + 3} becomes more stable for larger values of xx. I'll try with x0=2x_0 = 2 and run the calculation again.Using Newton's Method with an initial guess of x0=2x_0 = 2, the root of the function f(x)=x4x+3f(x) = x - 4\sqrt{x + 3} approximates to x18.583x \approx 18.583, accurate to three decimal places.

Would you like further clarification on the steps, or any additional details?

Here are some follow-up questions for deeper understanding:

  1. What are the conditions under which Newton's Method may fail to converge?
  2. How would you choose a better initial guess for Newton's Method?
  3. How does the rate of convergence of Newton's Method compare to other root-finding methods?
  4. Can you apply Newton’s Method to a different function and find its root?
  5. What is the significance of the derivative in Newton's Method, and what happens if it is zero?

Tip: Newton's Method requires that the derivative f(x)f'(x) not be zero at the starting guess. Always check for this condition before applying the formula.

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Math Problem Analysis

Mathematical Concepts

Calculus
Numerical Methods
Root Approximation

Formulas

Newton's Method iteration formula: x_{n+1} = x_n - f(x_n) / f'(x_n)
Derivative formula: f'(x) = 1 - 2 / √(x + 3)

Theorems

Newton's Method for Root Finding

Suitable Grade Level

Undergraduate Calculus or Numerical Methods