Math Problem Statement

using the newton-raphson method, find the sqrt(2) to 2 decimal places

Solution

To find the square root of 2 using the Newton-Raphson method to 2 decimal places, follow these steps:

The Newton-Raphson iteration formula is:

xn+1=xnf(xn)f(xn)x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)}

Here, we are solving f(x)=x22=0f(x) = x^2 - 2 = 0, so:

  • f(x)=x22f(x) = x^2 - 2
  • f(x)=2xf'(x) = 2x

Steps:

  1. Initial guess: Choose an initial guess close to the square root of 2, say x0=1.5x_0 = 1.5.
  2. Iteration: Compute xn+1x_{n+1} using the formula: xn+1=xnxn222xnx_{n+1} = x_n - \frac{x_n^2 - 2}{2x_n}
  3. Stop when the change between successive iterations is less than 0.01 (two decimal accuracy).

Iteration 1:

x1=x0x0222x0=1.51.52221.5x_1 = x_0 - \frac{x_0^2 - 2}{2x_0} = 1.5 - \frac{1.5^2 - 2}{2 \cdot 1.5} x1=1.52.2523=1.50.253=1.50.0833=1.4167x_1 = 1.5 - \frac{2.25 - 2}{3} = 1.5 - \frac{0.25}{3} = 1.5 - 0.0833 = 1.4167

Iteration 2:

x2=x1x1222x1=1.41671.41672221.4167x_2 = x_1 - \frac{x_1^2 - 2}{2x_1} = 1.4167 - \frac{1.4167^2 - 2}{2 \cdot 1.4167} x2=1.41672.006922.8334=1.41670.00692.8334=1.41670.0024=1.4143x_2 = 1.4167 - \frac{2.0069 - 2}{2.8334} = 1.4167 - \frac{0.0069}{2.8334} = 1.4167 - 0.0024 = 1.4143

Iteration 3:

x3=x2x2222x2=1.41431.41432221.4143x_3 = x_2 - \frac{x_2^2 - 2}{2x_2} = 1.4143 - \frac{1.4143^2 - 2}{2 \cdot 1.4143} x3=1.41432.0000064922.8286=1.41430.000006492.8286=1.41430.00000231.4142x_3 = 1.4143 - \frac{2.00000649 - 2}{2.8286} = 1.4143 - \frac{0.00000649}{2.8286} = 1.4143 - 0.0000023 \approx 1.4142

Result:

The square root of 2 to 2 decimal places is approximately:

1.41\boxed{1.41}

Would you like a more detailed explanation of any step?


Here are 5 related questions to expand on this:

  1. How does the Newton-Raphson method ensure convergence?
  2. What are other root-finding methods similar to Newton-Raphson?
  3. Can Newton-Raphson fail to converge, and under what conditions?
  4. How would you modify the Newton-Raphson method for functions with multiple roots?
  5. What is the general geometric interpretation of the Newton-Raphson iteration?

Tip: Always ensure your initial guess is reasonably close to the root for faster and reliable convergence.

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Math Problem Analysis

Mathematical Concepts

Numerical Methods
Newton-Raphson Method
Square Roots

Formulas

Newton-Raphson formula: x_{n+1} = x_n - f(x_n) / f'(x_n)
f(x) = x^2 - 2
f'(x) = 2x

Theorems

Newton-Raphson Convergence Theorem

Suitable Grade Level

Undergraduate or Advanced High School (Grades 11-12)