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Ch. 4 - Applications of the Derivative
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 4.R.56

{Use of Tech} Newton’s method Use Newton’s method to approximate the roots of ƒ(x) = e⁻²ˣ + 2eˣ - 6 to six digits.

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Identify the function for which we want to find the roots: \( f(x) = e^{-2x} + 2e^x - 6 \).
Compute the derivative of the function, \( f'(x) \), which is necessary for Newton's method. The derivative is \( f'(x) = -2e^{-2x} + 2e^x \).
Choose an initial guess \( x_0 \) for the root. A good starting point can be found by graphing the function or using prior knowledge about the behavior of exponential functions.
Apply Newton's method formula: \( x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)} \). Substitute \( f(x) \) and \( f'(x) \) into the formula to get \( x_{n+1} = x_n - \frac{e^{-2x_n} + 2e^{x_n} - 6}{-2e^{-2x_n} + 2e^{x_n}} \).
Iterate the process: Use the formula from the previous step to calculate \( x_1, x_2, \ldots \) until the difference between successive approximations is less than the desired tolerance (e.g., \( 10^{-6} \) for six-digit accuracy).

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Newton's Method

Newton's Method is an iterative numerical technique used to approximate the roots of a real-valued function. Starting with an initial guess, the method uses the function's derivative to refine the guess iteratively. The formula is x_{n+1} = x_n - f(x_n)/f'(x_n), where x_n is the current approximation. This process is repeated until a sufficiently accurate value is found.
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Exponential Functions

Exponential functions, such as e^x, are mathematical functions where the variable is in the exponent. They are characterized by rapid growth or decay, depending on the sign of the exponent. In the given function, e⁻²ˣ and eˣ represent exponential decay and growth, respectively, which influence the behavior and shape of the function's graph.
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Exponential Functions

Derivative Calculation

Calculating the derivative is essential in Newton's Method as it provides the slope of the tangent line at a given point. For the function ƒ(x) = e⁻²ˣ + 2eˣ - 6, the derivative is found using the rules of differentiation for exponential functions. This derivative is crucial for updating the approximation of the root in each iteration of Newton's Method.
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