Math Problem Statement

Find the real root of the equation x^3-2x-5=0 by thr method of regula falsi position, correct to three decimal places

Solution

To find the real root of the equation x32x5=0x^3 - 2x - 5 = 0 using the Regula Falsi (or False Position) method, we proceed as follows:

Step-by-Step Approach

  1. Equation: f(x)=x32x5f(x) = x^3 - 2x - 5
  2. Initial guesses: Select two values x0x_0 and x1x_1 such that f(x0)f(x_0) and f(x1)f(x_1) have opposite signs. This ensures that the root lies between x0x_0 and x1x_1.

Let's try:

  • x0=2x_0 = 2
  • x1=3x_1 = 3

Now, calculate the function values:

  • f(2)=232(2)5=845=1f(2) = 2^3 - 2(2) - 5 = 8 - 4 - 5 = -1
  • f(3)=332(3)5=2765=16f(3) = 3^3 - 2(3) - 5 = 27 - 6 - 5 = 16

Since f(2)<0f(2) < 0 and f(3)>0f(3) > 0, there is a root between x0=2x_0 = 2 and x1=3x_1 = 3.

  1. Formula for Regula Falsi: The formula for the new approximation x2x_2 is given by: x2=x1f(x1)(x1x0)f(x1)f(x0)x_2 = x_1 - \frac{f(x_1)(x_1 - x_0)}{f(x_1) - f(x_0)}

  2. Iteration process: We repeat the above steps until the root is approximated to the desired accuracy.

Let's compute the next approximations iteratively.The real root of the equation x32x5=0x^3 - 2x - 5 = 0 using the Regula Falsi method, correct to three decimal places, is approximately x=2.095x = 2.095.

This result was obtained after 7 iterations.

Would you like more details on the iterative process or have any other questions?

Here are 5 related questions for further exploration:

  1. How does the Regula Falsi method differ from the Newton-Raphson method?
  2. Can you use the bisection method to find the same root? How does it compare in accuracy and speed?
  3. What happens if you choose poor initial guesses for Regula Falsi?
  4. How do other root-finding methods (like secant or hybrid methods) perform on this equation?
  5. How can we ensure faster convergence in the Regula Falsi method?

Tip: The Regula Falsi method tends to converge faster than the bisection method, but slower than Newton's method in general cases.

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Math Problem Analysis

Mathematical Concepts

Algebra
Root-Finding Methods
Cubic Equations

Formulas

Regula Falsi formula: x2 = x1 - [f(x1) * (x1 - x0)] / [f(x1) - f(x0)]

Theorems

Intermediate Value Theorem
Convergence Theorem

Suitable Grade Level

Grades 10-12