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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.1.70d

In Exercises 67–72, you will explore some functions and their inverses together with their derivatives and tangent line approximations at specified points. Perform the following steps using your CAS:


d. Find the equation for the tangent line to g at the point (f(x_0), x_0) located symmetrically across the 45° line y=x (which is the graph of the identity function). Use Theorem 1 to find the slope of this tangent line.


70. y= x³/(x²+1), -1 ≤ x ≤ 1, x_0=1/2

Guida verificata passo dopo passo
1
Identify the given function as \( y = f(x) = \frac{x^3}{x^2 + 1} \) and the point \( x_0 = \frac{1}{2} \). The function \( g \) is the inverse of \( f \), so \( g = f^{-1} \). The point on \( g \) corresponding to \( x_0 \) is \( (f(x_0), x_0) \).
Calculate \( f(x_0) \) by substituting \( x_0 = \frac{1}{2} \) into \( f(x) \): \[ f\left(\frac{1}{2}\right) = \frac{\left(\frac{1}{2}\right)^3}{\left(\frac{1}{2}\right)^2 + 1} \]
Find the derivative \( f'(x) \) using the quotient rule: \[ f'(x) = \frac{(3x^2)(x^2 + 1) - x^3(2x)}{(x^2 + 1)^2} \] Then evaluate \( f'(x_0) \) at \( x_0 = \frac{1}{2} \).
Use Theorem 1, which states that the derivative of the inverse function at \( y_0 = f(x_0) \) is the reciprocal of the derivative of the original function at \( x_0 \): \[ g'(y_0) = \frac{1}{f'(x_0)} \] This gives the slope of the tangent line to \( g \) at the point \( (f(x_0), x_0) \).
Write the equation of the tangent line to \( g \) at \( (f(x_0), x_0) \) using point-slope form: \[ y - x_0 = g'(f(x_0)) (x - f(x_0)) \] where \( y \) and \( x \) are the coordinates on the graph of \( g \).

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Inverse Functions and Their Graphs

An inverse function reverses the roles of inputs and outputs of the original function, swapping x and y. Graphically, the inverse function's graph is the reflection of the original function's graph across the line y = x (the 45° line). Understanding this symmetry is crucial for locating points and tangent lines related to inverse functions.
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Inverse Tangent

Derivative of an Inverse Function (Theorem 1)

Theorem 1 states that if a function f is differentiable and invertible at x₀, then the derivative of its inverse g at y₀ = f(x₀) is given by g'(y₀) = 1 / f'(x₀). This relationship allows us to find the slope of the tangent line to the inverse function using the derivative of the original function.
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Derivatives of Other Inverse Trigonometric Functions

Tangent Line Equation and Point-Slope Form

The tangent line to a curve at a point is the best linear approximation of the function near that point. Its equation can be found using the point-slope form: y - y₁ = m(x - x₁), where m is the slope (derivative at the point) and (x₁, y₁) is the point of tangency. This is essential for writing the tangent line to g at (f(x₀), x₀).
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Percorso guidato
05:13
Slopes of Tangent Lines
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Domanda del libro di testo

2. Express the following logarithms in terms of ln 5 and ln 7.

d. ln 1225

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In Exercises 67–72, you will explore some functions and their inverses together with their derivatives and tangent line approximations at specified points. Perform the following steps using your CAS:

d. Find the equation for the tangent line to g at the point (f(x_0), x_0) located symmetrically across the 45° line y=x (which is the graph of the identity function). Use Theorem 1 to find the slope of this tangent line.

68. y= (3x+2)/(2x-11), -2 ≤ x ≤ 2, x_0=1/2

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Domanda del libro di testo

In Exercises 67–72, you will explore some functions and their inverses together with their derivatives and tangent line approximations at specified points. Perform the following steps using your CAS:

e. Plot the functions f and g, the identity, the two tangent lines, and the line segment joining the points (x_0, f(x_0)) and (f(x_0), x_0). Discuss the symmetries you see across the main diagonal y=x.


72. y= 2-x-x³, -2 ≤ x ≤ 2, x_0 = 3/2

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Domanda del libro di testo

In Exercises 67–72, you will explore some functions and their inverses together with their derivatives and tangent line approximations at specified points. Perform the following steps using your CAS:

d. Find the equation for the tangent line to g at the point (f(x_0), x_0) located symmetrically across the 45° line y=x (which is the graph of the identity function). Use Theorem 1 to find the slope of this tangent line.

67. y= √(3x-2), 2/3 ≤ x ≤ 4, x_0=3

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views
Domanda del libro di testo

In Exercises 67–72, you will explore some functions and their inverses together with their derivatives and tangent line approximations at specified points. Perform the following steps using your CAS:

d. Find the equation for the tangent line to g at the point (f(x_0), x_0) located symmetrically across the 45° line y=x (which is the graph of the identity function). Use Theorem 1 to find the slope of this tangent line.

72. y= 2-x-x³, -2 ≤ x ≤ 2, x_0 = 3/2

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6. Which of the following functions grow faster than ln(x) as x→∞? Which grow at the same rate as ln(x)? Which grow slower?

e. x - 2ln(x)

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