For what value of k the following piecewise defined function will be continuous? [k - 2 cos x, e4x+1 O f(x) = k = 2 k = 3 k=2+e k = 3 + e k=2-e x ≤ 0 x > 0

College Algebra
1st Edition
ISBN:9781938168383
Author:Jay Abramson
Publisher:Jay Abramson
Chapter3: Functions
Section3.3: Rates Of Change And Behavior Of Graphs
Problem 2SE: If a functionfis increasing on (a,b) and decreasing on (b,c) , then what can be said about the local...
Question
### Problem Statement

For what value of \( k \) the following piecewise defined function will be continuous?

\[
f(x) = 
\begin{cases} 
k - 2 \cos x, & x \leq 0 \\
e^{4x+1}, & x > 0 
\end{cases}
\]

### Answer Choices:
1. \( k = 2 \)
2. \( k = 3 \) (selected)
3. \( k = 2 + e \)
4. \( k = 3 + e \)
5. \( k = 2 - e \)

### Explanation:

To determine the value of \( k \) that makes the function \( f(x) \) continuous, we need to ensure that the limit from the left as \( x \) approaches 0 equals the limit from the right as \( x \) approaches 0, and both limits are equal to the function value at \( x = 0 \).

#### Left-Hand Limit as \( x \) approaches 0:
For \( x \leq 0 \), the function is \( f(x) = k - 2 \cos x \). As \( x \) approaches 0 from the left:
\[
\lim_{{x \to 0^-}} (k - 2 \cos x) = k - 2 \cos(0) = k - 2
\]

#### Right-Hand Limit as \( x \) approaches 0:
For \( x > 0 \), the function is \( f(x) = e^{4x+1} \). As \( x \) approaches 0 from the right:
\[
\lim_{{x \to 0^+}} e^{4x+1} = e^1 = e
\]

#### Equating the Limits:
To ensure continuity at \( x = 0 \):
\[
k - 2 = e
\]

Solving for \( k \):
\[
k = e + 2
\]

### Conclusion:
The piecewise function \( f(x) \) will be continuous if \( k = 2 + e \).

Since the selected answer \( k = 3 \) does not satisfy this condition, the correct answer should be \( k = 2 + e \).
Transcribed Image Text:### Problem Statement For what value of \( k \) the following piecewise defined function will be continuous? \[ f(x) = \begin{cases} k - 2 \cos x, & x \leq 0 \\ e^{4x+1}, & x > 0 \end{cases} \] ### Answer Choices: 1. \( k = 2 \) 2. \( k = 3 \) (selected) 3. \( k = 2 + e \) 4. \( k = 3 + e \) 5. \( k = 2 - e \) ### Explanation: To determine the value of \( k \) that makes the function \( f(x) \) continuous, we need to ensure that the limit from the left as \( x \) approaches 0 equals the limit from the right as \( x \) approaches 0, and both limits are equal to the function value at \( x = 0 \). #### Left-Hand Limit as \( x \) approaches 0: For \( x \leq 0 \), the function is \( f(x) = k - 2 \cos x \). As \( x \) approaches 0 from the left: \[ \lim_{{x \to 0^-}} (k - 2 \cos x) = k - 2 \cos(0) = k - 2 \] #### Right-Hand Limit as \( x \) approaches 0: For \( x > 0 \), the function is \( f(x) = e^{4x+1} \). As \( x \) approaches 0 from the right: \[ \lim_{{x \to 0^+}} e^{4x+1} = e^1 = e \] #### Equating the Limits: To ensure continuity at \( x = 0 \): \[ k - 2 = e \] Solving for \( k \): \[ k = e + 2 \] ### Conclusion: The piecewise function \( f(x) \) will be continuous if \( k = 2 + e \). Since the selected answer \( k = 3 \) does not satisfy this condition, the correct answer should be \( k = 2 + e \).
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