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Ch. 4 - Applications of the Derivative
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 4, Problem 4.8.31

{Use of Tech} Finding intersection points Use Newton’s method to approximate all the intersection points of the following pairs of curves. Some preliminary graphing or analysis may help in choosing good initial approximations.


y = 4√x and y = x² + 1

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1
Step 1: Set the equations equal to each other to find the intersection points. This means solving 4√x = x² + 1.
Step 2: Rearrange the equation to form a function f(x) = 4√x - x² - 1. This function represents the difference between the two curves.
Step 3: Use preliminary graphing or analysis to estimate initial guesses for the intersection points. Look for values of x where the curves appear to intersect.
Step 4: Apply Newton's method to approximate the intersection points. Newton's method uses the formula x_{n+1} = x_n - f(x_n)/f'(x_n), where f'(x) is the derivative of f(x).
Step 5: Calculate the derivative f'(x) = (2/x^(1/2)) - 2x. Use this derivative in Newton's method to iteratively refine your initial guesses until the values converge to the intersection points.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Newton's Method

Newton's Method is an iterative numerical technique used to find approximate solutions to equations. It starts with an initial guess and refines it using the formula x_{n+1} = x_n - f(x_n)/f'(x_n), where f is the function and f' is its derivative. This method is particularly useful for finding roots of functions, making it ideal for determining intersection points of curves.
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Intersection Points

Intersection points occur where two curves meet, meaning their y-values are equal for the same x-value. To find these points, one typically sets the equations of the curves equal to each other and solves for x. The solutions can then be substituted back into either original equation to find the corresponding y-values.
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Graphing and Analysis

Preliminary graphing and analysis involve plotting the functions to visually identify potential intersection points. This step helps in selecting appropriate initial guesses for Newton's Method, as the method's success often depends on starting close to the actual root. Understanding the behavior of the curves can also provide insights into the number and nature of intersection points.
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