   Chapter 4.6, Problem 4E ### Single Variable Calculus: Early Tr...

8th Edition
James Stewart
ISBN: 9781305270343

#### Solutions

Chapter
Section ### Single Variable Calculus: Early Tr...

8th Edition
James Stewart
ISBN: 9781305270343
Textbook Problem

# Produce graphs of f that reveal all the important aspects of the curve. In particular, you should use graphs of f′ and f″ to estimate the intervals of increase and decrease, extreme values, intervals of concavity, and inflection points. f ( x ) = x 4 − x 3 − 8 x 2 − x − 6

To determine

To sketch: The graph of f that reveals all important aspects of the curve and the graph of f' and f" to estimate the intervals of increase, decrease, the extreme values, the intervals of concavity and the inflection points.

Explanation

Given information:

The curve function is f(x)=x4x38x2x6 (1)

Calculation:

Equate Equation (1) equal to 0.

f(x)=0x4x38x2x6=0x4x38=0 (2)

Solve Equation (2).

x=1.48,2

Draw the graph of the function f by substituting different values for x.

The sketches of the function f with the important aspects are shown in Figure 1 and Figure 2.

Differentiate Equation (1) with respect to x.

f'(x)=(x2x6)(4x33x2)(x4x38)(2x1)(x2x6)2=4x54x424x33x4+3x3+18x22x5+x4+2x4x3+16x8(x2x6)2=2x54x422x3+18x2+16x8(x2x6)2=2(x52x411x3+9x2+8x4)(x2x6)2 (3)

Equate Equation (3) equal to 0.

f'(x)=02(x52x411x3+9x2+8x4)(x2x6)2=02(x52x411x3+9x2+8x4)=0 (4)

Solve Equation (4).

x=2.74,0.81,0.41,1.08,4.06

The sketches of the function f' with the important aspects are shown in Figure 3 and Figure 4.

Differentiate Equation (3) with respect to x.

f"(x)=[(x2x6)22(5x48x333x2+18x+8)(2(x52x411x3+9x2+8x4))(2(x2x6)(2x1))](x2x6)3 (5)

The sketches of the function f" with the important aspects are shown in Figure 5 and Figure 6.

Refer Figure 3 and Figure 4.

The curve f is decreasing on (,2.74) , (0.81,0.41) , (1.08,3) , and (3,4.06) .

The curve f is increasing on (2.74,2) , (2,0.81) , (0.41,1.08) , and (4.06,) .

The local minimum value occurs at x=2.74 , x=0.41 , and x=4.06 .

The local maximum value occurs at x=0.81 and x=1.08 .

Therefore, the intervals of increase is on (2.74,2)_ , (2,0

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started

#### Find more solutions based on key concepts 