Math Problem Statement

Find the root of the equation π‘₯ = 𝑒 βˆ’π‘₯ , using the Newton Raphson Method up to 4 th iteration.

Solution

To find the root of the equation x=eβˆ’xx = e^{-x} using the Newton-Raphson method, we need to:

  1. Rewrite the equation in the form f(x)=0f(x) = 0. We have: f(x)=xβˆ’eβˆ’xf(x) = x - e^{-x}

  2. The Newton-Raphson formula is given by: xn+1=xnβˆ’f(xn)fβ€²(xn)x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)} where fβ€²(x)f'(x) is the derivative of f(x)f(x).

Step 1: Compute fβ€²(x)f'(x)

We need the derivative of f(x)=xβˆ’eβˆ’xf(x) = x - e^{-x}: fβ€²(x)=1+eβˆ’xf'(x) = 1 + e^{-x}

Step 2: Newton-Raphson Iterations

  1. Initial Guess x0x_0: Let's assume an initial guess x0=0.5x_0 = 0.5.

  2. Iteration Formula: xn+1=xnβˆ’f(xn)fβ€²(xn)=xnβˆ’xnβˆ’eβˆ’xn1+eβˆ’xnx_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)} = x_n - \frac{x_n - e^{-x_n}}{1 + e^{-x_n}}

Now let's perform the iterations up to the 4th step.

First Iteration x1x_1:

f(x0)=0.5βˆ’eβˆ’0.5β‰ˆ0.5βˆ’0.60653=βˆ’0.10653f(x_0) = 0.5 - e^{-0.5} \approx 0.5 - 0.60653 = -0.10653 fβ€²(x0)=1+eβˆ’0.5β‰ˆ1+0.60653=1.60653f'(x_0) = 1 + e^{-0.5} \approx 1 + 0.60653 = 1.60653 x1=0.5βˆ’βˆ’0.106531.60653β‰ˆ0.5+0.06633=0.56633x_1 = 0.5 - \frac{-0.10653}{1.60653} \approx 0.5 + 0.06633 = 0.56633

Second Iteration x2x_2:

f(x1)=0.56633βˆ’eβˆ’0.56633β‰ˆ0.56633βˆ’0.56789=βˆ’0.00156f(x_1) = 0.56633 - e^{-0.56633} \approx 0.56633 - 0.56789 = -0.00156 fβ€²(x1)=1+eβˆ’0.56633β‰ˆ1+0.56789=1.56789f'(x_1) = 1 + e^{-0.56633} \approx 1 + 0.56789 = 1.56789 x2=0.56633βˆ’βˆ’0.001561.56789β‰ˆ0.56633+0.00099=0.56732x_2 = 0.56633 - \frac{-0.00156}{1.56789} \approx 0.56633 + 0.00099 = 0.56732

Third Iteration x3x_3:

f(x2)=0.56732βˆ’eβˆ’0.56732β‰ˆ0.56732βˆ’0.56732=0f(x_2) = 0.56732 - e^{-0.56732} \approx 0.56732 - 0.56732 = 0 fβ€²(x2)=1+eβˆ’0.56732β‰ˆ1+0.56732=1.56732f'(x_2) = 1 + e^{-0.56732} \approx 1 + 0.56732 = 1.56732 x3=0.56732βˆ’01.56732=0.56732x_3 = 0.56732 - \frac{0}{1.56732} = 0.56732

Fourth Iteration x4x_4:

Since f(x3)β‰ˆ0f(x_3) \approx 0, we can stop here as x4=x3=0.56732x_4 = x_3 = 0.56732.

Result:

The root of the equation x=eβˆ’xx = e^{-x} after 4 iterations using the Newton-Raphson method is approximately xβ‰ˆ0.56732x \approx 0.56732.

Would you like further details or have any questions?

Here are 5 questions to explore further:

  1. What are the conditions for convergence in the Newton-Raphson method?
  2. How can the initial guess affect the convergence of the method?
  3. Can Newton-Raphson fail, and in what cases?
  4. How would the method change for a system of nonlinear equations?
  5. What are alternative methods for solving nonlinear equations?

Tip: In numerical methods, starting with a good initial guess can significantly speed up the convergence process.

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Math Problem Analysis

Mathematical Concepts

Numerical Methods
Newton-Raphson Method
Exponential Functions
Calculus

Formulas

f(x) = x - e^{-x}
Newton-Raphson Iteration Formula: x_{n+1} = x_n - f(x_n) / f'(x_n)
f'(x) = 1 + e^{-x}

Theorems

Newton-Raphson Method

Suitable Grade Level

Undergraduate - Calculus/Numerical Analysis