EXAM Find the local minimum and maximum values of the function below. f(x) = 3x4 – 8x3 – 210x2 + 5 Video Example SOLUTION f'(x) 12x3 - 24x2 - 420x = 12x(x – 7)(x + 5) From the chart Interval 12x x - 7 x + 5| f'(x) f x < -5 decreasing on (-∞, -5) -5 < x < 0 increasing on (-5, 0) 0 < x < 7 decreasing on (0, 7) + + x > 7 + + increasing on (7, 0) we see that f'(x) changes from negative to positive at -5, so is a local minimum value by the First Derivative Test. f(-5) = Similarly, f'(x) changes from negative to positive at 7, so f(7) = is a local minimum value.
EXAM Find the local minimum and maximum values of the function below. f(x) = 3x4 – 8x3 – 210x2 + 5 Video Example SOLUTION f'(x) 12x3 - 24x2 - 420x = 12x(x – 7)(x + 5) From the chart Interval 12x x - 7 x + 5| f'(x) f x < -5 decreasing on (-∞, -5) -5 < x < 0 increasing on (-5, 0) 0 < x < 7 decreasing on (0, 7) + + x > 7 + + increasing on (7, 0) we see that f'(x) changes from negative to positive at -5, so is a local minimum value by the First Derivative Test. f(-5) = Similarly, f'(x) changes from negative to positive at 7, so f(7) = is a local minimum value.
College Algebra (MindTap Course List)
12th Edition
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:R. David Gustafson, Jeff Hughes
Chapter4: Polynomial And Rational Functions
Section4.1: Quadratic Functions
Problem 6SC: A company that makes and sells baseball caps has found that the total monthly cost C in dollars of...
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Question
![EXAMPLE 2 Find the local minimum and maximum values of the function
below.
f(x) = 3x4 – 8x3 – 210x2 + 5
Video Example
SOLUTION
f'(x)
12x3 – 24x2 – 420x = 12x(x – 7)(x + 5)
From the chart
Interval
12x x - 7
x + 5| f'(x)
f
x < -5
decreasing on (-∞, –5)
-
-5 < x < 0
+
increasing on (-5, 0)
0 < x < 7
decreasing on (0, 7)
+
x > 7
+
+
increasing on (7, 0)
we see that f'(x) changes from negative to positive at -5, so
is a local minimum value by the First Derivative Test.
f(-5) =
Similarly, f'(x) changes from negative to positive at 7, so f(7) =
is a
local minimum value.
And, f(0) =
is a local maximum value because f'(x) changes from
positive to negative at 0.
+](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F61d3fec5-12f7-45ef-a221-7ede5a9d6496%2Fdcb27d56-577c-4db4-9bde-75038b99cd07%2F24w0co_processed.jpeg&w=3840&q=75)
Transcribed Image Text:EXAMPLE 2 Find the local minimum and maximum values of the function
below.
f(x) = 3x4 – 8x3 – 210x2 + 5
Video Example
SOLUTION
f'(x)
12x3 – 24x2 – 420x = 12x(x – 7)(x + 5)
From the chart
Interval
12x x - 7
x + 5| f'(x)
f
x < -5
decreasing on (-∞, –5)
-
-5 < x < 0
+
increasing on (-5, 0)
0 < x < 7
decreasing on (0, 7)
+
x > 7
+
+
increasing on (7, 0)
we see that f'(x) changes from negative to positive at -5, so
is a local minimum value by the First Derivative Test.
f(-5) =
Similarly, f'(x) changes from negative to positive at 7, so f(7) =
is a
local minimum value.
And, f(0) =
is a local maximum value because f'(x) changes from
positive to negative at 0.
+
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