h f(4)= -2, f'(4)=3, g(4) = -4, and g'(4) = -2. Find an equation of the line tangent to the graph of F(x) = f(x)g(x) at x = 4.

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**Calculating the Equation of the Tangent Line**

*Problem Statement:*

Assume that functions \(f\) and \(g\) are differentiable with the following values:

- \(f(4) = -2\)
- \(f'(4) = 3\)
- \(g(4) = -4\)
- \(g'(4) = -2\)

Find an equation of the line tangent to the graph of \(F(x) = f(x)g(x)\) at \(x = 4\).

*Solution:*

To find the equation of the tangent line, we need to determine the derivative \(F'(x)\) using the product rule:

\[
F(x) = f(x) \cdot g(x)
\]

The product rule states that:

\[
F'(x) = f'(x)g(x) + f(x)g'(x)
\]

Substituting the given values at \(x = 4\):

\[
F'(4) = f'(4)g(4) + f(4)g'(4) = (3 \cdot -4) + (-2 \cdot -2) = -12 + 4 = -8
\]

The point on the curve at \(x = 4\) is:

- \(F(4) = f(4) \cdot g(4) = -2 \cdot -4 = 8\)

The equation of the tangent line in point-slope form is:

\[
y - F(4) = F'(4)(x - 4)
\]

Substituting the known values:

\[
y - 8 = -8(x - 4)
\]

Simplifying:

\[
y = -8x + 32 + 8 = -8x + 40
\]

*Conclusion:*

The equation of the tangent line is:

\[
y = -8x + 40
\]
Transcribed Image Text:**Calculating the Equation of the Tangent Line** *Problem Statement:* Assume that functions \(f\) and \(g\) are differentiable with the following values: - \(f(4) = -2\) - \(f'(4) = 3\) - \(g(4) = -4\) - \(g'(4) = -2\) Find an equation of the line tangent to the graph of \(F(x) = f(x)g(x)\) at \(x = 4\). *Solution:* To find the equation of the tangent line, we need to determine the derivative \(F'(x)\) using the product rule: \[ F(x) = f(x) \cdot g(x) \] The product rule states that: \[ F'(x) = f'(x)g(x) + f(x)g'(x) \] Substituting the given values at \(x = 4\): \[ F'(4) = f'(4)g(4) + f(4)g'(4) = (3 \cdot -4) + (-2 \cdot -2) = -12 + 4 = -8 \] The point on the curve at \(x = 4\) is: - \(F(4) = f(4) \cdot g(4) = -2 \cdot -4 = 8\) The equation of the tangent line in point-slope form is: \[ y - F(4) = F'(4)(x - 4) \] Substituting the known values: \[ y - 8 = -8(x - 4) \] Simplifying: \[ y = -8x + 32 + 8 = -8x + 40 \] *Conclusion:* The equation of the tangent line is: \[ y = -8x + 40 \]
Expert Solution
Step 1

Given :

Assume that the functions f and g are differentiable with f4=-2,f'4=3,g4=-4 and g'4=-2.

To find :

The equation of the line tangent to the graph of Fx=fxgx at x=4.

Formula used :

(1) Product rule of differentiation is ddxfg=gf'+fg'.

(2) The equation of tangent line with slope m at the point x0,y0 is y-y0=mx-x0.

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