Given the function f(x) = (x + 1)(x- 2). Find the interval where f(x) is increasing and decreasing.

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter4: Polynomial And Rational Functions
Section4.6: Variation
Problem 8E
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35.no 4 do like example given solution

INCREASING & DECREASING FUNCTIONS
) be a function difforentiable in the open interval (a,b)
(x) is an increasing function. (positive slope).
1(x) is a decreasing function. (negative slope).
( 3).
(3,2).
(2.).
r(x) is increasing
1(x) is decreasing
1(x) is increasing
Example 1:
Determine the interval where f (x) = 2 - 3x + 4x is increasing & decreasing.
Solution:
f(x) increasing, f'(x) > 0
- 3 + 8x
8x
> 0
> 3
3.
8
f(x) increasing in the interval
f(x) decreasing, f'(x) < 0
< 0
3
8
-3 + 8x
f(x) decreasing in the interval (- o,)
Example 2: Show that y =
X
+ e2x+1
is an increasing function for all x.
X + 1
Solution:
y
+ e2x+1
x + 1
dy
dx
(x + 1 )(1) – (1)(x)
+ e*+* (2)
(x + 1)
(x +1)²
+ 2e?*+ 1
(x + 1.
> 0 for all x and 2e2x+1 >0 for all x
y =
+ ex+1
X + 1
is an increasing function for all x
Transcribed Image Text:INCREASING & DECREASING FUNCTIONS ) be a function difforentiable in the open interval (a,b) (x) is an increasing function. (positive slope). 1(x) is a decreasing function. (negative slope). ( 3). (3,2). (2.). r(x) is increasing 1(x) is decreasing 1(x) is increasing Example 1: Determine the interval where f (x) = 2 - 3x + 4x is increasing & decreasing. Solution: f(x) increasing, f'(x) > 0 - 3 + 8x 8x > 0 > 3 3. 8 f(x) increasing in the interval f(x) decreasing, f'(x) < 0 < 0 3 8 -3 + 8x f(x) decreasing in the interval (- o,) Example 2: Show that y = X + e2x+1 is an increasing function for all x. X + 1 Solution: y + e2x+1 x + 1 dy dx (x + 1 )(1) – (1)(x) + e*+* (2) (x + 1) (x +1)² + 2e?*+ 1 (x + 1. > 0 for all x and 2e2x+1 >0 for all x y = + ex+1 X + 1 is an increasing function for all x
2x - 5x is a decreasing function in the interval (-1, 5).
7. Find the interval where f (x) is increasing
TUTORIAL 35
12x - 5. Find the intervals where
Given a function f(x) = 2x +3x
1(x) is increasing and decreasing.
2.
Given f(x) = 4x + 15x- 18x
3.
Show that f(x) =
Given the function f(x) = (x + 1)(x - 2).
Find the interval where f(x) is increasing and decreasing.
5x
Given the function f(x) =
5.
Find the interval where f (x) is increasing or decreasing.
6.
Given the function f(x) =
1 + x
Find the interval where f(x) is increasing or decreasing.
Given the function f (x) =
X - 4
Find the interval where f (x) is increasing or decreasing.
8.
Given the function f (x)
X- 2
X + 2
Find the interval where f(x) is increasing or decreasing.
Answers:
Increasing (-,-2) U (1,)
Decreasing : (-2,1)
1.
Increasing : (-, -3) u (5.)
Increasing: (-,0) u (2,)
Decreasing: (0,2)
5.
2.
4.
Decreasing: (-, 2) u (2,)
Increasing: (-,-1) U (-1, )
Decreasing: (-«, 4) U (4.)
Increasing: (-,-2) (-2, )
Transcribed Image Text:2x - 5x is a decreasing function in the interval (-1, 5). 7. Find the interval where f (x) is increasing TUTORIAL 35 12x - 5. Find the intervals where Given a function f(x) = 2x +3x 1(x) is increasing and decreasing. 2. Given f(x) = 4x + 15x- 18x 3. Show that f(x) = Given the function f(x) = (x + 1)(x - 2). Find the interval where f(x) is increasing and decreasing. 5x Given the function f(x) = 5. Find the interval where f (x) is increasing or decreasing. 6. Given the function f(x) = 1 + x Find the interval where f(x) is increasing or decreasing. Given the function f (x) = X - 4 Find the interval where f (x) is increasing or decreasing. 8. Given the function f (x) X- 2 X + 2 Find the interval where f(x) is increasing or decreasing. Answers: Increasing (-,-2) U (1,) Decreasing : (-2,1) 1. Increasing : (-, -3) u (5.) Increasing: (-,0) u (2,) Decreasing: (0,2) 5. 2. 4. Decreasing: (-, 2) u (2,) Increasing: (-,-1) U (-1, ) Decreasing: (-«, 4) U (4.) Increasing: (-,-2) (-2, )
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